build(deps): move @intx/* to 0.4.0 (CL-8797)

[TheGreatAxios]

Summary

Moves the sole @intx/* dependency to 0.4.0.

Package	Before	After
@intx/db	0.2.2	0.4.0

This was a two-minor-version jump (0.2.2 → 0.4.0). No workspace:* entries were present, so no substitution was needed.

Code changes

None. typecheck and the full test suite pass unchanged against 0.4.0 — the @intx/db symbols this repo consumes (DB type, schema re-exports: principal, tenant, user, grant, principalRole, role) are unaffected by the API changes between 0.2.2 and 0.4.0.

README code fences were reviewed; none reference @intx/db APIs (they use corbits-tag/slack and @chat-adapter/state-postgres only), so none needed updating.

Checks (baseline main @intx/db 0.2.2 → this branch @intx/db 0.4.0)

• bun run typecheck: clean → clean
• bun run test: 150 pass / 0 fail → 150 pass / 0 fail (same counts)
• No lint/format scripts exist in this repo (CI runs only typecheck and test)
• Lockfile refreshed with bun install; no stray lockfiles from other package managers

Part of CL-8797