refactor(sdlc): 消除四個 SDLC skill 間重複邏輯，改為委派唯一權威來源

What（做了什麼）：
1. 移除 plan、analyze、implement 三個 skill 及 README.md 中各自重述的 wiki hash 演算法說明（原本各處都各自寫一遍「取 SHA-1 前 8 碼大寫十六進位，開頭若為數字或 A/B/C 則替換為 H 加後 7 碼」），改為統一指向唯一權威工具 jsc-gitea/tools/hash-id（透過 jsc-gitea:wiki 使用）。
2. 移除 plan、analyze、implement、maintain 四個 skill 中重複的 model chain fallback 選擇邏輯說明（原本各自描述「執行 jsc-cli/tools/model-config.sh get {stage}，若印出 chain 則取目前 CLI 可用的第一個，fallback 依 chain 順序套用」），改為統一呼叫新的共用子指令 jsc-cli/tools/model-config.sh resolve {stage}，由該子指令自行封裝解析邏輯（此 resolve 子指令由另一位 agent 同時在 sibling repo jsc-cli 開的配套 PR 新增，本 PR 依賴該 PR）。
3. implement/SKILL.md 移除自身多餘的「先解析環境變數」步驟（原第 2 步，手動檢查 JSC_WIKI_REPO_ANALYZE、JSC_WIKI_REPO、JSC_WIKI_REPO_QUESTION、GITEA_HOST、GITEA_TOKEN 後才詢問使用者），因為此解析已由 implement 其他步驟委派的 jsc-gitea:wiki 正確處理，屬於死重複邏輯；後續步驟由 2-8 重新編號為 2-7。
4. maintain/SKILL.md 在 frontmatter description 欄位加入明確的負向觸發說明，釐清此 skill 僅用於已交付、仍在維護窗口內的專案，「不適用於仍在實作中或尚未登錄於 MAINTAIN_CONTENTS 的專案」。
5. plugin.json、.claude-plugin/plugin.json、.codex-plugin/plugin.json 三份版本號檔案，由 0.0.3 升版至 0.0.4。

Why（為什麼改）：
四個 SDLC skill 各自重述相同的 hash 演算法與 model chain fallback 邏輯，違反 jsc-meta:skill-check 稽核準則中「單一權威來源」的要求，日後維護容易改一處漏一處；implement 的環境變數解析步驟與其他步驟委派的 jsc-gitea:wiki 功能重疊，屬死碼；maintain 的觸發時機描述不夠明確，容易被誤用在尚未進入維護窗口的專案上。

How（怎麼改的）：
將重複邏輯抽離，改為指向或呼叫唯一權威工具/skill（jsc-gitea/tools/hash-id、jsc-cli/tools/model-config.sh resolve、jsc-gitea:wiki），移除 implement 中的死步驟並重新編號，於 maintain frontmatter 補上負向觸發描述，並同步升版三份 plugin.json。全程不改變任何對外行為，純屬重構。

Who（誰／哪個需求）：
jsc-meta:skill-check 對 plan、analyze、implement、maintain 四個 SDLC skill 的例行合規稽核修正。

skills/implement/SKILL.md

@@ -11,18 +11,17 @@ All wiki reads and writes go through `jsc-gitea:wiki`.
 ## Steps
 
 1. **Model gate and stage lock**:
-   1. Resolve the implement stage's designated model chain: run `jsc-cli/tools/model-config.sh get implement`. If it prints a chain, the required model is the first entry of the chain the current CLI can use (fallbacks apply in chain order). If it prints nothing, fall back to the capability-tag check via `jsc-cli:models` (implementation requires the coding tag).
+   1. Run `jsc-cli/tools/model-config.sh resolve implement` to get the required model; if it prints nothing, fall back to the capability-tag check via `jsc-cli:models` (implementation requires the coding tag).
    2. If the current model is not the required model, or fails the tag check, block the flow and tell the user which model to switch to. Completion condition: the current model satisfies the gate.
    3. Lock the stage: run `jsc-hooks/hooks/sdlc-gate.sh lock implement {current-model}`. From now until the next SDLC stage's gate runs, the sdlc-gate hook enforces this model on every prompt; switching models mid-stage gets blocked. Completion condition: the lock file is written, verified with `sdlc-gate.sh report`.
-2. **Resolve environment first**: inspect `JSC_WIKI_REPO_ANALYZE`, `JSC_WIKI_REPO`, `JSC_WIKI_REPO_QUESTION`, `GITEA_HOST`, and `GITEA_TOKEN` before asking the user anything. Use inherited shell values first. If the env vars are present but the tool cannot read them, check the current shell environment before asking.
-3. **Generate a work ticket**: format `TICKET_{yyyyMMdd}_{HHmmss}_{HASH}`. Use the shared wiki hash for `{owner}/{repo}` for `{HASH}`: take the first 8 uppercase hex chars of its SHA-1, then replace a leading digit or `A`/`B`/`C` with `H` plus the next 7 chars. Try to rename the current session to the ticket name (skip when the CLI does not support it).
-4. Read `ANALYZE_CONTENTS` via `jsc-gitea:wiki` and list what is unfinished: plan name, HASH, work package number, count of open items. A selectable work package must satisfy all three: **unfinished, dependency-free (or all dependencies done), and not holding a work ticket**.
-5. Let the user pick a work package per `jsc-ask:ask` rules (options state open-item count and estimated effort). Write the ticket into that work package's ticket column (the zh-TW field 「工作證」) on the analysis page and save it back to the wiki. **Only after the ticket is saved successfully may you proceed.**
-6. List every open item of the work package and implement them **one at a time**:
+2. **Generate a work ticket**: format `TICKET_{yyyyMMdd}_{HHmmss}_{HASH}`. `{HASH}` = the shared wiki hash for `{owner}/{repo}`, computed by `jsc-gitea/tools/hash-id` (see `jsc-gitea:wiki`). Try to rename the current session to the ticket name (skip when the CLI does not support it).
+3. Read `ANALYZE_CONTENTS` via `jsc-gitea:wiki` and list what is unfinished: plan name, HASH, work package number, count of open items. A selectable work package must satisfy all three: **unfinished, dependency-free (or all dependencies done), and not holding a work ticket**.
+4. Let the user pick a work package per `jsc-ask:ask` rules (options state open-item count and estimated effort). Write the ticket into that work package's ticket column (the zh-TW field 「工作證」) on the analysis page and save it back to the wiki. **Only after the ticket is saved successfully may you proceed.**
+5. List every open item of the work package and implement them **one at a time**:
    - Follow the TDD loop: red before green, one slice at a time; rules and anti-patterns in `references/tdd.md` (refactoring belongs to the review stage).
    - After each item, flip its `[ ]` to `[x]` on the analysis page and save to the wiki before starting the next item.
-7. When all items are done, call `jsc-review:code-review` and wait for the review; on failure, fix and re-review until it passes.
-8. Ask per `jsc-ask:ask` rules whether to register this project for maintenance: append to `MAINTAIN_CONTENTS` with `templates/maintain-contents.md`. Required: repository `{owner}/{repo}`, maintenance method, start date. Optional: end date (NULL = maintain forever), last-maintained time.
+6. When all items are done, call `jsc-review:code-review` and wait for the review; on failure, fix and re-review until it passes.
+7. Ask per `jsc-ask:ask` rules whether to register this project for maintenance: append to `MAINTAIN_CONTENTS` with `templates/maintain-contents.md`. Required: repository `{owner}/{repo}`, maintenance method, start date. Optional: end date (NULL = maintain forever), last-maintained time.
 
 ## Rules