feat: safety hook skills + skill usage telemetry (v0.7.1) (#189)

* feat: add /careful, /freeze, /guard, /unfreeze safety hook skills

Four new on-demand skills using Claude Code's PreToolUse hooks:
- /careful: warns before destructive commands (rm -rf, DROP TABLE, force-push, etc.)
- /freeze: blocks file edits outside a specified directory
- /guard: composes both into one command
- /unfreeze: clears freeze boundary without ending session

Pure bash hook scripts with Python fallback for JSON edge cases.
Safe exceptions for build artifacts (node_modules, dist, .next, etc.).
Hook fire telemetry logs pattern name only (never command content).

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

* feat: add skill usage telemetry to preamble

TemplateContext system passes skill name through resolver pipeline so
each generated SKILL.md gets its own name baked into the telemetry line.
Appends to ~/.gstack/analytics/skill-usage.jsonl on every invocation.

Covers 14 preamble-using skills + 4 hook skills (inline telemetry).
JSONL format: {"skill":"ship","ts":"...","repo":"my-project"}

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

* feat: add analytics CLI for skill usage stats

bun run analytics reads ~/.gstack/analytics/skill-usage.jsonl and shows
top skills, per-repo breakdown, hook fire stats, and daily timeline.
Supports --period 7d/30d/all. Handles missing/empty/malformed data.

22 unit tests cover parsing, filtering, formatting, and edge cases.

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

* feat: add skills-used-this-week to /retro

Retro Step 2 now reads skill-usage.jsonl and shows which gstack skills
were used during the retro window. Follows the same pattern as the
Greptile signal and Backlog Health metrics — read file, filter by date,
aggregate, present. Skips silently if no analytics data exists.

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

* test: add hook script and telemetry tests

32 unit tests for check-careful.sh covering all 8 destructive patterns,
safe exceptions, Python fallback, and malformed input handling.
7 unit tests for check-freeze.sh covering boundary enforcement,
trailing slash edge case, and missing state file.
Telemetry tests verify per-skill name correctness in generated output.
Adds careful/freeze/guard/unfreeze/document-release to ALL_SKILLS.

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

* chore: bump version to 0.6.5 + changelog + mark TODOs shipped

Safety hook skills and skill usage telemetry shipped.
Analytics CLI and /retro integration included.

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

* feat: /debug auto-freezes edits to the module being debugged

Add PreToolUse hooks (Edit/Write) to debug/SKILL.md.tmpl that reference
the existing freeze/bin/check-freeze.sh. After Phase 1 investigation,
/debug locks edits to the narrowest affected directory.

Graceful degradation: if freeze script is unavailable, scope lock is
skipped. Users can run /unfreeze to remove the restriction.

Deferred 6 enhancements to TODOS.md, gated on telemetry showing the
freeze hook actually fires in real debugging sessions.

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

---------

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

document-release/SKILL.md

@@ -33,6 +33,8 @@ _BRANCH=$(git branch --show-current 2>/dev/null || echo "unknown")
 echo "BRANCH: $_BRANCH"
 _LAKE_SEEN=$([ -f ~/.gstack/.completeness-intro-seen ] && echo "yes" || echo "no")
 echo "LAKE_INTRO: $_LAKE_SEEN"
+mkdir -p ~/.gstack/analytics
+echo '{"skill":"document-release","ts":"'$(date -u +%Y-%m-%dT%H:%M:%SZ)'","repo":"'$(basename "$(git rev-parse --show-toplevel 2>/dev/null)" 2>/dev/null || echo "unknown")'"}'  >> ~/.gstack/analytics/skill-usage.jsonl 2>/dev/null || true
 _PROACTIVE=$(~/.claude/skills/gstack/bin/gstack-config get proactive 2>/dev/null || echo "true")
 echo "PROACTIVE: $_PROACTIVE"
 ```