fix(coderabbit): resolve all 12 findings on PR #3152

MAJOR (security/correctness):
- commands/gsd/debug.md: add Write to allowed-tools (session file creation
  requires it — workflow explicitly says 'use Write tool, never heredoc')
- workflows/debug.md: add SLUG sanitization guard to steps 1b+1c (status/
  continue subcommands used raw user input in file paths — path traversal)
- workflows/thread.md: sanitize $ARGUMENTS in RESUME mode before file path
  construction (was bypassing the sanitization guard in CLOSE/STATUS modes)

MINOR (consistency/correctness):
- docs/INVENTORY-MANIFEST.json: remove stale top-level 'workflows' array
  (duplicate of families.workflows introduced in earlier update)
- commands/gsd/resume-work.md: normalize process to 'Execute end-to-end.'
- commands/gsd/settings.md: normalize process to 'Execute end-to-end.'
- commands/gsd/update.md: normalize otherwise branch to 'execute end-to-end.'
- docs/adr/0002: add Status: Accepted + Date header (ADR convention)
- workflows/extract-learnings.md: rename step extract_learnings → extract-learnings
- tests/extract-learnings.test.cjs: tighten step-name assertion to exact name

ARCHITECTURE:
- scripts/command-contract-helpers.cjs: extract CANONICAL_TOOLS, parseFrontmatter,
  executionContextRefs as shared module — single source of truth consumed by
  both lint script and test suite (prevents silent lint/test disagreement)
- scripts/lint-command-contract.cjs: require() helpers instead of duplicating
- tests/command-contract.test.cjs: require() helpers; move readFileSync calls
  inside test() callbacks (registration-time throws surface as named failures)

get-shit-done/workflows/thread.md

@@ -117,7 +117,11 @@ No agent spawn. STOP after printing.
 <mode_resume>
 **RESUME mode:**
 
-If $ARGUMENTS matches an existing thread name (file `.planning/threads/{ARGUMENTS}.md` exists):
+If $ARGUMENTS matches an existing thread name:
+
+**Sanitize first:** apply the same slug sanitization used by CLOSE and STATUS — strip any characters not matching `[a-z0-9-]`, reject slugs longer than 60 chars or containing `..` or `/`. If invalid, output "Invalid thread slug." and stop. Use the sanitized value as SLUG for all subsequent file path construction.
+
+Check `.planning/threads/{SLUG}.md` exists. If not, fall through to CREATE mode.
 
 Resume the thread — load its context into the current session. Read the file content and display it as plain text. Ask what the user wants to work on next.