feat: Firefox selection translation extension with local Ollama (initial version)

Implement the complete initial version of a Firefox WebExtension (Manifest V3)
that translates selected text on web pages using a local Ollama LLM and shows
the result in a small popover near the selection.

Specification alignment (Phase 0)
- Unified Specifications.md / Design.md / Security.md on the same approach:
  Ollama REST API + Fetch API + NDJSON streaming (no ollama-js SDK dependency)
- Fixed host_permissions to http://localhost/* and http://127.0.0.1/* because
  Firefox match patterns do not support port numbers (bug 1362809/1468162);
  the actual connection target is restricted to localhost/127.0.0.1 + any port
  by application-side validation (defense in depth, OLL-09)
- Clipboard: use navigator.clipboard.writeText() only inside the copy button
  click (user activation); no deprecated execCommand fallback

Implementation (zero dependencies, vanilla JS, no npm/Node required)
- manifest.json: MV3, background.scripts + type:module (event page, no
  service_worker), action popup, options_ui, content_scripts for http/https,
  permissions: storage + localhost host permissions only
- src/shared: constants (ports, limits, presets, error codes), message
  validation, settings schema (defaults / merge / sanitize / buildOptions /
  toApiThinking), system prompt builder (fixed prompt first + user prompt)
- src/background: message-router (runtime.Port streaming + runtime.onMessage
  for model list), translation-session (single active request, abort previous
  on new request, stale chunk suppression), ollama-client (fetch against
  /api/tags and /api/chat with buffering NDJSON line parser tolerant to chunk
  boundaries inside JSON objects, AbortController, host re-validation before
  every request, HTTP status to error-code mapping), settings-service
  (storage.local load/save with validation and fallback to defaults)
- src/content/content.js: single classic script (Firefox does not support ES
  modules in content scripts) with selection detection (selectionchange +
  mouseup + keyup, debounced), Shadow DOM action button, Shadow DOM popover
  with HIDDEN/LOADING/STREAMING/COMPLETED/ERROR state machine, port client
  with requestId-based stale chunk filtering, enabled-state sync via
  storage.onChanged; all dynamic text rendered via textContent only
- src/popup + src/options: full settings UI (enable toggle, Ollama host,
  model list from Ollama with saved-model warning, target language, thinking
  mode, temperature slider 0.0-2.0 step 0.1, context length presets
  4k/8k/16k/32k/128k/256k, seed random/fixed with integer value, user system
  prompt, advanced numeric options with steppers, stop sequences textarea)
- icons generated by tools/make-icons.ps1 (System.Drawing, no external tools)
- build.ps1 packages manifest.json + icons/ + src/ into dist zip, excluding
  tests/, doc/, ollama-js/ and tools/

Tests (71 passed, 0 failed)
- In-browser test runner (tests/test.html) with custom describe/it/assert
  framework; no npm, no Node.js
- Unit: constants sync between content mirror and shared module, Ollama host
  validation (localhost/127.0.0.1 + any port only; rejects external hosts,
  LAN IPs, https, credentials, paths), settings schema defaults and fallback,
  temperature 0.1-step validation, context length presets, seed modes,
  advanced option types, buildOptions omission of unset values and absence of
  tfs_z/mirostat fields, system prompt composition order, message validation
  with selection length boundary values
- Integration: NDJSON streaming across awkward byte boundaries, thinking
  chunk forwarding, malformed line tolerance, error payload mapping, think/
  options inclusion rules, model list, TranslationSession abort semantics,
  settings round-trip with storage.onChanged cache refresh, full port flow
  (started/chunk/completed), newer request aborts older with stale chunk
  discard, malformed message rejection, OLLAMA_UNAVAILABLE and
  INVALID_SETTINGS error paths, untrusted sender rejection

Security audit (Design.md section 24 checklist: all pass)
- No innerHTML/outerHTML/document.write/eval/new Function/localStorage
- No remote JS/CSS/fonts/CDN resources; no inline scripts in extension pages
- Ollama access limited to background; content scripts never fetch Ollama
- Background validates message type/length/requestId; single concurrent
  translation enforced
- Clipboard API only (no execCommand fallback)
- Minimal permissions: storage + localhost host permissions

Docs
- README.md with build/load/usage instructions, API list, permission rationale
- doc/Testing-Results.md with automated test results, security audit results,
  and a 14-item manual Firefox verification checklist (to be executed on a
  real Firefox + Ollama environment)

1 files changed, 128 insertions, 0 deletions

diff --git a/tests/runner.js b/tests/runner.js
new file mode 100644
index 0000000..bfafa10
--- /dev/null
+++ b/tests/runner.js
@@ -0,0 +1,128 @@
+/**
+ * Minimal in-browser test runner (no npm / no Node).
+ * Provides describe/it/assert and renders results into the document.
+ */
+(() => {
+  'use strict';
+
+  const suites = [];
+  let currentSuite = null;
+  const results = [];
+
+  /**
+   * @param {string} name
+   * @param {() => void} fn
+   */
+  function describe(name, fn) {
+    currentSuite = { name, tests: [] };
+    suites.push(currentSuite);
+    fn();
+    currentSuite = null;
+  }
+
+  /**
+   * @param {string} name
+   * @param {() => void|Promise<void>} fn
+   */
+  function it(name, fn) {
+    if (!currentSuite) throw new Error('it() outside describe()');
+    currentSuite.tests.push({ name, fn });
+  }
+
+  class AssertionError extends Error {}
+
+  /**
+   * @param {*} actual
+   * @param {*} expected
+   * @param {string} [message]
+   */
+  function assertEqual(actual, expected, message) {
+    const a = JSON.stringify(actual);
+    const b = JSON.stringify(expected);
+    if (a !== b) {
+      throw new AssertionError(message || `expected ${b}, got ${a}`);
+    }
+  }
+
+  /**
+   * @param {*} actual
+   * @param {string} [message]
+   */
+  function assertTrue(actual, message) {
+    if (actual !== true) {
+      throw new AssertionError(message || `expected true, got ${JSON.stringify(actual)}`);
+    }
+  }
+
+  /**
+   * @param {*} actual
+   * @param {string} [message]
+   */
+  function assertFalse(actual, message) {
+    if (actual !== false) {
+      throw new AssertionError(message || `expected false, got ${JSON.stringify(actual)}`);
+    }
+  }
+
+  /**
+   * @param {number} actual
+   * @param {number} expected
+   * @param {number} epsilon
+   * @param {string} [message]
+   */
+  function assertCloseTo(actual, expected, epsilon, message) {
+    if (Math.abs(actual - expected) > epsilon) {
+      throw new AssertionError(message || `expected ~${expected}, got ${actual}`);
+    }
+  }
+
+  /**
+   * @param {Function} fn
+   * @param {string} [message]
+   */
+  async function assertThrowsAsync(fn, message) {
+    try {
+      await fn();
+    } catch {
+      return;
+    }
+    throw new AssertionError(message || 'expected function to throw');
+  }
+
+  async function run() {
+    const root = document.getElementById('results');
+    const summary = document.getElementById('summary');
+    let passed = 0;
+    let failed = 0;
+
+    for (const suite of suites) {
+      const suiteEl = document.createElement('section');
+      const heading = document.createElement('h2');
+      heading.textContent = suite.name;
+      suiteEl.append(heading);
+
+      for (const test of suite.tests) {
+        const row = document.createElement('div');
+        row.className = 'test';
+        try {
+          await test.fn();
+          passed++;
+          row.classList.add('pass');
+          row.textContent = `✔ ${test.name}`;
+        } catch (error) {
+          failed++;
+          row.classList.add('fail');
+          row.textContent = `✘ ${test.name} — ${error && error.message ? error.message : String(error)}`;
+        }
+        suiteEl.append(row);
+      }
+      root.append(suiteEl);
+    }
+
+    summary.textContent = `${passed} passed, ${failed} failed`;
+    summary.className = failed === 0 ? 'all-pass' : 'has-failures';
+    document.title = failed === 0 ? 'PASS - Tests' : 'FAIL - Tests';
+  }
+
+  window.TestRunner = { describe, it, assertEqual, assertTrue, assertFalse, assertCloseTo, assertThrowsAsync, run };
+})();
\ No newline at end of file