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- tasks/LESSONS.md deleted (empty template; superseded by learnings.md)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/journal.md

@@ -0,0 +1,22 @@
+---
+type: journal
+schema:
+  entry: one date heading per working session
+  body: 3-5 lines max - what was done, decided, blocked
+rules:
+  - One heading per date (YYYY-MM-DD), not per session.
+  - Append at the end. Never edit past entries.
+  - Keep it terse. Details belong in decisions/learnings/blockers - this is a timeline only.
+---
+
+# Journal
+
+<!-- Append new date-heading entries below. Template:
+
+## YYYY-MM-DD
+
+- <ligne 1>
+- <ligne 2>
+- <ligne 3-5 max>
+
+-->