docs: drop mentions of the deleted agent-directory and agent-runtime packages (CL-8587)

[TheGreatAxios]

Summary

• The agent-directory and agent-runtime packages were already deleted (refactor(tools)!: delete agent-directory package; agent-directory tools use stock routes (CL-8466) #891/refactor(tools)!: delete hub-calling tool packages; Myra ships stock tools-mail and tools-posix (CL-8471) #892); only stale doc/comment mentions of them remained.

Changes

• Deleted docs/agent-definition-status-lifecycle.md: entirely described the removed @corbits/agent-directory route, and nothing else links to it.
• Reworded docs/workflow-definition-projection.md to name the current launch target (the bundled deploy source in apps/web/src/agent-deploy.ts) instead of the deleted @corbits/agent-runtime.
• Reworded the visibleAgents comment in apps/web/src/query-client.ts to point at the stock GET /workflows/definitions listing it actually uses via listAgentDefinitions.

Testing

• bun run check (typecheck/lint/fmt pass; pre-existing unrelated sidecar test timeouts/flakes, not touched by this change)

[linear-code]

CL-8587