Add warden trust-review director for permission and plugin paths

[TheGreatAxios]

Implements CL-7657: new closed leaf director warden.

Warden is a trust reviewer for permission / provider-auth / plugin-loader diffs only. It writes findings on grant-matching holes, secret-guard bypasses, arktype boundary skips, shell-policy peel gaps, and plugin trust, and never ships fixes (same never-fix posture as critic).

Skywalker mention is tiny by design: warden's trigger line plus one routing sentence added to the orchestrator prompt, and warden appended to the spawn allowlist.

Fixes CL-7657

[linear-code]

CL-7657

[TheGreatAxios]

Audit (Warden director): Approve with nits.

Findings:

• Budgets + routing present; identity follows convention (You are WardenDirector (Warden)).
• Docs: README-only on this PR (vs full set on Add a Gauntlet director that mutation-checks tests can actually fail #977, none on Add measure-only prober leaf director #962/Add Migrator director for reversible data migrations #963) — fine as-is; use Add a Gauntlet director that mutation-checks tests can actually fail #977 as the template if fuller docs are wanted later.
• Collision: same 16->17 bump as Add a Gauntlet director that mutation-checks tests can actually fail #977/Add measure-only prober leaf director #962/Add Migrator director for reversible data migrations #963 in types.ts, registry.test.ts, registry.ts, skywalker allowlist, prompt-sizes.test.ts.
• Sequencing: land Add a Gauntlet director that mutation-checks tests can actually fail #977 first, then rebase this PR to 18/19/20 during merge phase. Do NOT stack onto sibling branches.
• No code fix required on this PR — comment only.