fix(skills): replace sqlite3 CLI with in-tree better-sqlite3 wrapper

Setup deliberately avoids the sqlite3 CLI (`setup/verify.ts:5` calls
this out: "Uses better-sqlite3 directly (no sqlite3 CLI)") and never
installs or probes for the binary. Despite that, 13 skills shelled out
to `sqlite3 ...` directly, breaking on hosts where the CLI isn't
preinstalled — the same root cause as #2191 but spread across the
skill surface.

Add `scripts/q.ts`, a ~30-LOC wrapper over the `better-sqlite3` dep
that setup already installs and verifies. Default output matches
`sqlite3 -list` (pipe-separated, no header) so existing skill text
reads identically — only the binary changes. SELECT/WITH queries go
through `db.prepare().all()`; everything else (INSERT/UPDATE/DELETE,
including compound statements) goes through `db.exec()`.

Migrate every in-tree caller:

- 17 hardcoded invocations across 8 SKILL.md files (init-first-agent,
  add-deltachat, add-signal, add-emacs, add-whatsapp, add-ollama-provider,
  debug, add-parallel) plus add-deltachat/VERIFY.md.
- `manage-channels/SKILL.md` shows canonical SQL but never prescribed
  a tool, so the assistant defaulted to `sqlite3` and silently failed.
  Add a one-line wrapper hint above the SQL block.
- `migrate-v2.sh` schema/count probes (was the original #2191 case).
  Replace `.tables` with `SELECT name FROM sqlite_master`.
- Document the wrapper convention in root `CLAUDE.md` under "Central DB".

Add `scripts/q.test.ts` with 6 vitest cases covering both modes,
NULL rendering, empty-result, compound mutations, and arg validation.
Wire `scripts/**/*.test.ts` into `vitest.config.ts`.

Out of scope (flagged for follow-up):
- `debug` and `add-parallel` still reference the v1-only path
  `store/messages.db`. Routing through the wrapper now produces a
  cleaner "no such file" error, but the surrounding sections are
  v1-era throughout — a v1-content cleanup is its own PR.
- `cleanup-sessions.sh` is being addressed in #1889 (different style,
  hard-fail rather than wrap); left untouched here to avoid stepping
  on that author's work.

Closes #2191.

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

.claude/skills/add-signal/SKILL.md

@@ -200,7 +200,7 @@ systemctl --user restart nanoclaw
 After the service starts, send any message to the Signal number from your personal Signal app. The router auto-creates a `messaging_groups` row. Then:
 
 ```bash
-sqlite3 data/v2.db \
+pnpm exec tsx scripts/q.ts data/v2.db \
   "SELECT id, platform_id FROM messaging_groups WHERE channel_type='signal' ORDER BY created_at DESC LIMIT 5"
 ```
 
@@ -212,7 +212,7 @@ Add the Signal number to a group from your phone, send any message, then wire th
 
 ```bash
 NOW=$(date -u +"%Y-%m-%dT%H:%M:%S.000Z")
-sqlite3 data/v2.db "
+pnpm exec tsx scripts/q.ts data/v2.db "
 INSERT OR IGNORE INTO messaging_group_agents
   (id, messaging_group_id, agent_group_id, session_mode, priority, created_at)
 VALUES
@@ -226,7 +226,7 @@ New Signal users (including the owner's Signal identity) are silently dropped wi
 
 ```bash
 NOW=$(date -u +"%Y-%m-%dT%H:%M:%S.000Z")
-sqlite3 data/v2.db "
+pnpm exec tsx scripts/q.ts data/v2.db "
 INSERT OR REPLACE INTO user_roles (user_id, role, agent_group_id, granted_by, granted_at)
   VALUES ('signal:UUID', 'owner', NULL, 'system', '$NOW');
 INSERT OR IGNORE INTO agent_group_members (user_id, agent_group_id, added_by, added_at)
@@ -282,7 +282,7 @@ If you see `Signal daemon not reachable at 127.0.0.1:7583` and `SIGNAL_MANAGE_DA
 ### Bot not responding
 
 1. Channel initialized: `grep "Signal channel connected" logs/nanoclaw.log | tail -1`
-2. Channel wired: `sqlite3 data/v2.db "SELECT mg.platform_id, mg.name FROM messaging_groups mg JOIN messaging_group_agents mga ON mg.id = mga.messaging_group_id WHERE mg.channel_type='signal'"`
+2. Channel wired: `pnpm exec tsx scripts/q.ts data/v2.db "SELECT mg.platform_id, mg.name FROM messaging_groups mg JOIN messaging_group_agents mga ON mg.id = mga.messaging_group_id WHERE mg.channel_type='signal'"`
 3. Service running: `launchctl print gui/$(id -u)/com.nanoclaw` (macOS) / `systemctl --user status nanoclaw` (Linux)
 
 ### Lost connection mid-session