[codex] Implement agent architecture controller surfaces

[kwannoel]

Summary

Implements the controller-side surfaces for the agent architecture plan, including daemon gateway routing, chat agent routing controls, profile creation/editing workspace, workspace snapshot linking, and observability UI for chat metrics and agent traces.

Impact

• Routes daemon access through the controller gateway without exposing daemon auth to the browser.
• Adds profile creation/editing, route-token UI, chat metrics, and agent trace views.
• Adds tests for gateway behavior, chat routing, profile UI, metrics rendering, and observability views.

Validation

• pnpm check
• pnpm test
• cargo +stable fmt --check
• cargo +stable clippy -- -D warnings
• cargo +stable test
• npx playwright test --project=e2e e2e/specs/observability.spec.ts
• Targeted sensitive-info scan over branch diff: no private keys, GitHub/OpenAI/AWS token-shaped values, bearer values, or suspicious secret assignments found.

Draft because the paired daemon PR should land with this work.