feat(memory): introduce .claude/{tasks,memory,audits}/ governance layout

Move tasks/ into .claude/tasks/ and create .claude/memory/ with 5
persistent registries (decisions/learnings/blockers/journal/evals) plus
.claude/audits/ for audit reports. Also seed templates/memory/ for
onboarder to copy into user projects.

- tasks/TODO.md, tasks/rtk-upstream-issue.md → .claude/tasks/
- tasks/LESSONS.md deleted (empty template; superseded by learnings.md)
- .claude/memory/: 5 append-only registries with YAML schema + seed entries
- templates/memory/: 5 empty-index templates for new projects

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

templates/memory/blockers.md

@@ -0,0 +1,34 @@
+---
+type: blockers_registry
+entry_prefix: BLK
+schema:
+  id: BLK-XXX
+  date: YYYY-MM-DD
+  friction: string (what was blocked)
+  real_cause: string (root cause, not symptom)
+  solution: string (workaround or fix)
+  status: [open | resolved | upstream]
+rules:
+  - Open a blocker as soon as friction > 15 min wasted. Close it with a real cause, not "moved on".
+  - Link to upstream issue / PR / commit when applicable.
+  - If cause is a bug in a dependency, set status upstream with a pointer to the tracker.
+---
+
+# Blockers registry (BLK)
+
+## Index
+
+| ID | Date | Friction | Status |
+|----|------|---------|--------|
+
+<!-- Append entries below. Template:
+
+## BLK-XXX - <friction>
+
+- **Date** : YYYY-MM-DD
+- **Friction** : <ce qui était bloqué>
+- **Cause réelle** : <cause racine>
+- **Solution** : <workaround ou fix>
+- **Statut** : open | resolved | upstream
+
+-->