fix: options page never ran due to missing export; unify settings handling

Root cause of the broken options page (audit finding):
- options.js imported CONTEXT_PRESETS from settings-schema.js, but that
  module never exported it. A named-import mismatch in ES modules is a
  SyntaxError, so the entire options page script silently never executed.
  This is why the settings page rendered its static HTML but was dead:
  no language options, no model list, no save handler.

Fixes
- options.js: import CONTEXT_PRESETS from shared/constants.js (where it
  is defined) instead of settings-schema.js
- options.js: save flow now merges the validated form over the stored
  settings (sanitize again) so fields saved by the popup in the meantime
  are preserved instead of being dropped
- popup.js: populate language options inside loadSettings and sanitize
  settings before every save, matching the options page behavior
- settings-schema.js: add normalizeOllamaHost() and use it in
  sanitizeSettings so trailing-slash variants are stored identically
- content.js: consolidate popover state - remove the duplicate outer
  lastSourceText and keep regenerate source inside the popover module;
  regenerate now calls portClient.translate directly

Test hardening (would have caught the original bug)
- tests/ui-smoke-tests.js: new smoke tests that install a fake browser
  API, run the real popup.js / options.js page scripts as ES modules
  against representative markup, and assert that language options are
  populated, the model select is filled from the mocked model list, and
  the stored host is reflected. The runner result elements are preserved
  across the sandboxed DOM swap
- test.html: include the smoke test module

Results: 73 passed, 0 failed (71 existing + 2 smoke). dist rebuilt.

0 files changed, 0 insertions, 0 deletions