feat: mount canonical gitea-workflow skill for Codex and MCP inventory (Closes #551)

Expose gitea-workflow / llm-project-workflow / git-pr-workflows as one
workflow router in mcp_list_project_skills, add preflight + Codex install
script, and document multi-runtime skill name parity.

docs/llm-workflow-runbooks.md

@@ -408,6 +408,25 @@ The guard blocks when the **control checkout** (repository root) is:
 `branches/...` directories are disposable role worktrees; the root checkout is
 the stable orchestration surface only.
 
+
+## Canonical workflow skill names (#551)
+
+Controller prompts and sessions must load the **same** workflow skill wall
+regardless of runtime (Claude, Codex, Gemini):
+
+| Name | Role |
+|------|------|
+| `gitea-workflow` | Primary controller / Codex skill name |
+| `llm-project-workflow` | Portable in-repo package |
+| `git-pr-workflows` | Legacy alias |
+
+- Inventory: `mcp_list_project_skills` lists all three.
+- Preflight: `mcp_check_workflow_skill_preflight` before mutations.
+- Codex install: `scripts/install-codex-workflow-skill.sh`
+- Full doc: [`docs/workflow-skill-mount.md`](workflow-skill-mount.md)
+
+If the skill is missing, stop with BLOCKED + DIAGNOSE — do not mutate.
+
 ## Shell Spawn Hard-Stop Rule
 
 Symptom: a shell tool call returns `exit_code: -1` with empty stdout/stderr.