feat: GitLab support for /retro, /ship, and /document-release (v0.11.20.0) (#508)

* feat: multi-platform BASE_BRANCH_DETECT (GitHub + GitLab + GHE + git-native)

Update the shared BASE_BRANCH_DETECT resolver to support GitHub, GitLab,
GitHub Enterprise, self-hosted GitLab, and a git-native fallback chain.
Platform detection uses remote URL matching plus CLI auth status for
custom domains. Add glab issue create alternative in test failure triage.

Add 7 new test assertions covering GitLab CLI presence, git symbolic-ref
fallback, and platform-specific output in retro and ship generated files.

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

* feat: GitLab support in /retro — use shared BASE_BRANCH_DETECT resolver

Replace retro's custom gh-only default branch detection with the shared
BASE_BRANCH_DETECT resolver (DRY — same as 10 other skills). Update
PR/MR number extraction to match both GitHub #NNN and GitLab !NNN
patterns. Remove hardcoded github.com URL from the personal card footer.
Regenerate all SKILL.md files affected by the resolver update.

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

* feat: GitLab MR creation in /ship + /document-release

Ship Step 1.5 now checks .gitlab-ci.yml for release workflows alongside
GitHub Actions. Step 8 routes to glab mr create on GitLab repos with
correct flag mapping (-b, -t, -d). Falls back to manual instructions
when no CLI is available. Document-release now reads MR body via
glab mr view -F json and updates via glab mr update on GitLab repos.

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

* chore: add P2 TODO for land-and-deploy GitLab support

Track the remaining work to support GitLab in /land-and-deploy — MR
merge, CI polling, and deploy workflow detection using glab equivalents.

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

* fix: adversarial review — GitLab gate, shell safety, MR prefix preservation

Three fixes from adversarial review:
1. land-and-deploy: add GitLab gate after Step 0 — prevents detection/
   execution mismatch where agent detects GitLab but all subsequent
   steps are GitHub-only
2. document-release: use heredoc for glab mr update body to avoid shell
   metacharacter mangling ($, backticks, !) in MR descriptions
3. retro: preserve original #/! prefix in PR/MR number extraction —
   GitLab !42 stays as !42, not incorrectly converted to #42

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

* fix: resolve merge conflicts — deduplicate gen-skill-docs resolvers

The merge from main created duplicate RESOLVERS records in gen-skill-docs.ts
(inline functions shadowing the imported module versions). Removed the inline
duplicates so the modular resolvers from scripts/resolvers/ are used.
Also added missing E2E_TIERS entries for plan-completion/verification tests.

* chore: bump version and changelog (v0.11.20.0)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

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

ship/SKILL.md.tmpl

@@ -100,12 +100,13 @@ service with existing deployment — verify that a distribution pipeline exists.
 2. If new artifact detected, check for a release workflow:
    ```bash
    ls .github/workflows/ 2>/dev/null | grep -iE 'release|publish|dist'
+   grep -qE 'release|publish|deploy' .gitlab-ci.yml 2>/dev/null && echo "GITLAB_CI_RELEASE"
    ```
 
 3. **If no release pipeline exists and a new artifact was added:** Use AskUserQuestion:
    - "This PR adds a new binary/tool but there's no CI/CD pipeline to build and publish it.
      Users won't be able to download the artifact after merge."
-   - A) Add a release workflow now (GitHub Actions cross-platform build + GitHub Releases)
+   - A) Add a release workflow now (CI/CD release pipeline — GitHub Actions or GitLab CI depending on platform)
    - B) Defer — add to TODOS.md
    - C) Not needed — this is internal/web-only, existing deployment covers it
 
@@ -485,12 +486,13 @@ git push -u origin <branch-name>
 
 ---
 
-## Step 8: Create PR
+## Step 8: Create PR/MR
 
-Create a pull request using `gh`:
+Create a pull request (GitHub) or merge request (GitLab) using the platform detected in Step 0.
 
-```bash
-gh pr create --base <base> --title "<type>: <summary>" --body "$(cat <<'EOF'
+The PR/MR body should contain these sections:
+
+```
 ## Summary
 <bullet points from CHANGELOG>
 
@@ -534,11 +536,30 @@ gh pr create --base <base> --title "<type>: <summary>" --body "$(cat <<'EOF'
 - [x] All Vitest tests pass (N tests)
 
 🤖 Generated with [Claude Code](https://claude.com/claude-code)
+```
+
+**If GitHub:**
+
+```bash
+gh pr create --base <base> --title "<type>: <summary>" --body "$(cat <<'EOF'
+<PR body from above>
 EOF
 )"
 ```
 
-**Output the PR URL** — then proceed to Step 8.5.
+**If GitLab:**
+
+```bash
+glab mr create -b <base> -t "<type>: <summary>" -d "$(cat <<'EOF'
+<MR body from above>
+EOF
+)"
+```
+
+**If neither CLI is available:**
+Print the branch name, remote URL, and instruct the user to create the PR/MR manually via the web UI. Do not stop — the code is pushed and ready.
+
+**Output the PR/MR URL** — then proceed to Step 8.5.
 
 ---