feat: extract canonical work-issue workflow from monolithic skill (Closes #333)

Add workflows/work-issue.md with full author/coder gates (§0–§30),
work-issue final-report schema, task-mode router entry, start-issue template
link, and doc-contract tests.

Part of #333 workflow split (#334 review-merge extraction remains in PR #335).

skills/llm-project-workflow/SKILL.md

@@ -17,6 +17,26 @@ The core promise: **an LLM never does unsafe or untracked work.** Every change
 is tracked by an issue, isolated in its own worktree, reviewed by a different
 identity, and cleaned up only after a real merge.
 
+## Task mode router (#333)
+
+**Identify task mode before any mutation.** Load the matching workflow file and
+final-report schema; do not apply rules from other modes.
+
+| Task mode | Workflow | Final report schema |
+|-----------|----------|---------------------|
+| `work-issue` | [`workflows/work-issue.md`](workflows/work-issue.md) (canonical; §0–§30) | [`schemas/work-issue-final-report.md`](schemas/work-issue-final-report.md) |
+| `review-merge-pr` | `workflows/review-merge-pr.md` (planned — #334) | `schemas/review-merge-final-report.md` (planned) |
+| `create-issue` | `workflows/create-issue.md` (planned — #333) | `schemas/create-issue-final-report.md` (planned) |
+
+Mode isolation:
+
+- **work-issue** — author namespace; implement, validate, commit, PR; no approve/merge
+- **review-merge-pr** — reviewer namespace only; no issue creation, no code edits
+- **create-issue** — author namespace; duplicate search + `create_issue` capability; no PR review/merge
+
+For a full work-issue run, load [`workflows/work-issue.md`](workflows/work-issue.md)
+instead of relying on the §E summary below.
+
 ---
 
 
@@ -225,6 +245,10 @@ Worktree folder = branch with `/` replaced by `-`
 
 ## E. Start-work workflow
 
+**Canonical author workflow:** [`workflows/work-issue.md`](workflows/work-issue.md)
+(§0–§30). The steps below are a compact summary; load the workflow file for
+gates, proof wording, mutation ledger, and controller handoff schema.
+
 0. Acquire or verify a work lease (Work Selection Rule) — complete all seven
    checks before any claim, branch, or PR work.
 0b. Global LLM Worktree Rule — prove project root, `cwd`, branch, main-checkout