tool: add sqliteQueryTool

[EmersonBraun]

Area

tools package

Why

Local-first agents frequently need SQL without standing up Postgres.

Notes

Read-only by default; opt-in write mode; parameter sanitization.

Checklist

• Implementation
• Tests (unit + contract where applicable)
• Docs page under /docs/reference + deep-dive under the relevant tab
• Changeset (patch or minor)
• Example recipe cross-linked