feat(learn): 新增技能教訓紀錄與查閱技能及 LEARN wiki 頁範本

What：新增 skills/learn/SKILL.md（record／consult 兩種模式）與 templates/learn-page.md、templates/learn-contents.md 兩份 wiki 頁範本。
Why：參考 oh-my-pi 的 learn 工具，讓技能執行後能把教訓沉澱下來、執行前能先查閱套用，避免同樣的問題重複發生。
How：教訓以六欄表格（日期、技能、CLI、情境、教訓、下次做法）逐列附加到 LEARN_{HASH}，並同步更新 LEARN_CONTENTS 目錄；HASH 依共用 8 碼 wiki hash 規則（含 H 前綴退回），wiki 位置依 JSC_WIKI_REPO_LEARN → JSC_WIKI_REPO 解析，讀寫皆透過 jsc-gitea:wiki。
Who：jsc-log domain 的 learn 技能（教訓紀錄與查閱功能）。

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

skills/learn/SKILL.md

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+---
+name: learn
+description: Record a lesson learned after a skill run to wiki LEARN_{HASH} plus LEARN_CONTENTS, or consult past lessons before a skill run. Each entry is one table row with date, skill, CLI, situation, lesson, and next-time approach. HASH follows the shared 8-char rule with the H-prefix fallback. Use when a skill run produced a reusable lesson, or before running a skill to consult past lessons; not for work-time logs (see worklog).
+---
+
+# learn — lessons learned
+
+Close the loop on skill runs: record what a run taught you, consult it before the next run. Two modes — `record` and `consult`. Page content is chart-first Traditional Chinese (STE100): markdown table entries, prose as the last resort.
+
+## Target pages
+
+- Directory page: `LEARN_CONTENTS`. Content page: `LEARN_{HASH}`, one page per repository.
+- Compute `{HASH}` from `{owner}/{repo}` with `jsc-gitea/tools/hash-id` (shared wiki hash rule: first 8 uppercase SHA-1 hex chars; `H` plus the first 7 chars when the raw hash starts with `0-9`, `A`, `B`, or `C`).
+- Wiki repo resolution: `JSC_WIKI_REPO_LEARN` first, then `JSC_WIKI_REPO`. Inspect the inherited shell environment variables first; ask the user per the `jsc-ask:ask` rules only when neither resolves. Never borrow another type's `JSC_WIKI_REPO_{TYPE}`.
+- All wiki reads and writes go through `jsc-gitea:wiki`.
+
+## Mode: record
+
+Run after a skill run that produced a reusable lesson.
+
+1. Collect the six facts below. Done when every field has a value.
+
+   | # | Field (page column) | Source |
+   | --- | --- | --- |
+   | 1 | 日期 | Today, `yyyy-MM-dd` |
+   | 2 | 技能 | The skill that ran, as `jsc-{domain}:{name}` |
+   | 3 | CLI | One of claude / codex / copilot / antigravity / kiro |
+   | 4 | 情境 | What was happening when the lesson appeared, one sentence |
+   | 5 | 教訓 | What the run taught, one sentence |
+   | 6 | 下次做法 | How to apply it on the next run, one sentence |
+
+2. Resolve `{owner}/{repo}` from `git remote get-url origin` and compute `{HASH}` with `jsc-gitea/tools/hash-id`. Done when the page name `LEARN_{HASH}` is known.
+3. Write the entry. This step MUST run as a sub agent; the main agent only confirms the write succeeded.
+   - Read `LEARN_{HASH}` via `jsc-gitea:wiki`. If it does not exist, create it from `templates/learn-page.md`; otherwise APPEND the new row at the end of the table. Never overwrite existing rows.
+   - Update `LEARN_CONTENTS` in the same pass (apply `templates/learn-contents.md`; add the repo row if missing, otherwise refresh its 最後更新時間).
+   - Done when the sub agent reports both pages written and the main agent has confirmed the row exists on `LEARN_{HASH}`.
+
+## Mode: consult
+
+Run before a skill run, to apply past lessons.
+
+1. Resolve `{owner}/{repo}` and compute `{HASH}` as in record mode. Done when `LEARN_{HASH}` is known.
+2. Read `LEARN_CONTENTS` and the repo's `LEARN_{HASH}` via `jsc-gitea:wiki`. When either page is missing (exit 4), report 「無教訓紀錄」 and let the caller proceed. Done when both pages are read or reported missing.
+3. Surface every row whose 技能 matches the skill about to run, and summarize each matched 下次做法 for the caller to apply. Done when the matched rows (or 「無相符教訓」) are reported.

templates/learn-contents.md

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+# 教訓目錄
+
+> 由 `jsc-log:learn` 維護。這是教訓目錄頁 `LEARN_CONTENTS`。每個存取庫一列；`LEARN_{HASH}` 的 `{HASH}` 依共用 wiki hash 規則產生：先取 `{owner}/{repo}` 的 SHA-1 前 8 碼並轉成大寫；首碼若是 `0-9`、`A`、`B`、`C`，改用 `H` 加上原前 7 碼，總長維持 8 碼。
+
+| 存取庫名稱 | 教訓紀錄 | 最後更新時間 |
+| --- | --- | --- |
+| {owner}/{repo} | [[LEARN_{HASH}]] | {yyyy-MM-dd HH:mm} |

templates/learn-page.md

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+# 教訓紀錄 — {owner}/{repo}
+
+> 由 `jsc-log:learn` 維護。這是教訓紀錄頁 `LEARN_{HASH}`；`HASH` 依共用 wiki hash 規則產生。新教訓**附加**一列在表尾，不覆蓋舊列。執行技能前先查這頁，套用「下次做法」。
+
+| 日期 | 技能 | CLI | 情境 | 教訓 | 下次做法 |
+| --- | --- | --- | --- | --- | --- |
+| {yyyy-MM-dd} | {jsc-domain:name} | {claude、codex、copilot、antigravity、kiro 五選一} | {當時發生什麼事} | {這次學到什麼} | {下次怎麼做} |