fix: Codex description limit + wrong-repo bug

Move skill routing table from root SKILL.md.tmpl description (1017/1024
chars) to body where there's no length limit. Add 900-char warning
threshold test. Add -C flag to all codex exec calls so Codex always
runs in the correct git root directory.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

review/SKILL.md.tmpl

@@ -46,7 +46,10 @@ Before reviewing code quality, check: **did they build what was requested — no
    **If no PR exists:** rely on commit messages and TODOS.md for stated intent — this is the common case since /review runs before /ship creates the PR.
 2. Identify the **stated intent** — what was this branch supposed to accomplish?
 3. Run `git diff origin/<base>...HEAD --stat` and compare the files changed against the stated intent.
-4. Evaluate with skepticism:
+
+{{PLAN_COMPLETION_AUDIT_REVIEW}}
+
+4. Evaluate with skepticism (incorporating plan completion results if available):
 
    **SCOPE CREEP detection:**
    - Files changed that are unrelated to the stated intent