feat: personal access tokens with scoped bearer auth

Add cnp_ personal access tokens so the CLI, MCP server, and external
agents authenticate without a browser session — the agent-first spine
from ROADMAP2 phase A. Modeled on agent_auth_tokens: raw token shown
once, only SHA-256 hash stored.

- user_tokens table (goose migration + sqlc), name/prefix/scope/expiry,
  owner-scoped revoke, last_used_at stamping
- middleware: cnp_ bearer resolution, read scope gates mutations with
  403 SCOPE_INSUFFICIENT, non-admin scopes cap is_admin even for admin
  owners — a token never outranks its scope or its owner
- GET/POST/DELETE /api/v1/user/tokens + OpenAPI + generated types
- Settings UI: create with scope/expiry pickers, one-time token display
  with copy, list with last-used/expiry, confirm-revoke
- docs: OPERATIONS.md section, README feature line

Verified end-to-end against live Postgres: create/list/revoke, read
scope blocks PUT (403), write PAT on admin owner blocked from admin
routes (403), admin scope works, revoked token returns 401.

Authored By: TDvorak <[email protected]>

docs/guides/OPERATIONS.md

@@ -90,3 +90,30 @@ backend restart.
 once), copy the prefilled install command, revoke tokens when done. Agents
 register over `POST /api/agents/register` and heartbeat via
 `POST /api/agents/heartbeat`.
+
+## Personal access tokens
+
+**Settings → Personal Access Tokens**: issue `cnp_…` bearer tokens for the
+CLI, MCP server, and scripts — the same privileges as your account, bounded
+by scope. The raw token is shown once at creation; only its SHA-256 hash is
+stored.
+
+Scopes:
+
+- `read` — `GET`/`HEAD`/`OPTIONS` only; mutations return `403 SCOPE_INSUFFICIENT`.
+- `write` — everything except admin routes.
+- `admin` — full access; requires a platform admin account, and the token is
+  still capped at the owner's privileges.
+
+A token can never outrank its owner: non-admin scopes report
+`is_admin = false` even on admin accounts.
+
+```
+GET    /api/v1/user/tokens            list (metadata only, never hashes)
+POST   /api/v1/user/tokens            {name, scope?, expires_in_days?} → raw token once
+DELETE /api/v1/user/tokens/:id        revoke (owner-scoped)
+```
+
+Use as `Authorization: Bearer cnp_…`, or `containr auth login cnp_…`.
+Revocation takes effect on the next request; `last_used_at` updates on each
+authenticated call.