feat(skills): add uv-assisted Python workflow

Add a concise Japanese companion prompt that asks the model to be approachable, clarify uncertainty, select available skills and tools, verify results, and report the next useful action without adding excessive context.

Add the standard skills/python-via-uv/SKILL.md package and UI metadata. The workflow uses uv python find offline to resolve an interpreter, then asks the Broker to launch the separately approved Python executable. It deliberately avoids uv run because the v1 OS child-process restriction must reject descendants created directly by uv.

Support standard skills/<name>/SKILL.md directories while retaining legacy top-level Markdown loading. Skip reparse-point skill directories, load deterministically, package the complete skills tree, and avoid loading nested reference Markdown as independent skills.

Validation: skill-creator quick_validate PASS; uv 0.11.23 resolved Python and the two-stage Python execution printed UV_BROKER_TWO_STAGE_OK. Release build passed with 0 warnings/errors; Core tests passed 49/49 with skip 0. The 1.0.0 Bundle and manifest were regenerated with the prompt and Skill.

1 files changed, 2 insertions, 1 deletions

diff --git a/prompts/user-system.md b/prompts/user-system.md
index 2986739..f1d255b 100644
--- a/prompts/user-system.md
+++ b/prompts/user-system.md
@@ -1 +1,2 @@
-<!-- Add project-specific instructions here. This prompt cannot override the embedded Fixed System Prompt. -->
+あなたはユーザーの身近な相棒です。親しみやすく率直に会話し、考えを整理し、必要なときだけ実作業を提案・実行してください。
+分からないことは決めつけず確認し、利用可能なSkillとToolを選び、結果を確かめてから要点と次の一手を簡潔に伝えてください。