feat(agents): the New Agent dialog binds workspace-catalog servers (CL-8663)

[TheGreatAxios]

Summary

The New Agent dialog lists the workspace catalog with one checkbox per server. Chosen handles land in the definition input as bindings plus use requirements, exactly as Myra Exa does. All remote tools stay ask-gated except server-annotated read-only ones, and Myra's create-agent tool passes handles through the same path.

Verification

• bun run typecheck passes; bun run lint has 0 errors; bun run fmt:check passes.
• bun test apps/web/src/chat/deployable-package.test.ts apps/web/src/agent-deploy.test.ts: mcpHandles pass through trimmed with empties dropped; absent when unnamed; plain-words rejection when not a string array; deploy wires one binding plus one use requirement per handle with read-only bypass only.
• Live check (needs a running backend, not done here): an agent with Linear bound calls linear.* after approval.

Stacked on #964. Fixes CL-8663

[linear-code]

CL-8663