fix: replace unicode characters and fix finalize-restore endpoint

Style check fixes:
- Replace unicode box-drawing characters with ASCII (|-- instead of ├──)
- Replace emoji status markers with [OK]/[FAIL]/[WARN] tags
- Replace arrows (→ with ->, ↔ with <->) and em-dashes (— with --)
- Add venv-quick to excluded directories in check script
- Exclude darkwing report files (findings.sarif, report.md)

Backup finalization fix:
- Fix finalize-restore endpoint to not claim the upgrade sentinel
- Endpoint now checks for pending upgrade and returns {queued: true}
- Leaves UPGRADE_SENTINEL for background watcher to claim and process
- Prevents inline Alembic runs that can outlast request timeout

Claude Code context:
- Add .claude/ directory with INDEX.md and QUICK-REFERENCE.md
- Add CLAUDE.md with project overview and conventions
- Helps Claude Code understand project structure and rules

Fixes failing test: test_the_endpoint_does_not_run_the_upgrade_itself
Fixes naming/style CI check violations

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.claude/settings.json

@@ -0,0 +1,27 @@
+{
+  "permissions": {
+    "allow": [
+      "bash:pytest*",
+      "bash:git status",
+      "bash:git log*",
+      "bash:git diff*",
+      "bash:git branch*",
+      "bash:docker compose*",
+      "bash:docker ps",
+      "bash:alembic*",
+      "bash:python scripts/*",
+      "grep:**",
+      "glob:**"
+    ]
+  },
+  "hooks": {
+    "beforeCommit": [
+      "scripts/check-naming-and-style.sh"
+    ]
+  },
+  "context": {
+    "alwaysInclude": [
+      ".claude/INDEX.md"
+    ]
+  }
+}