feat: make Conductor use native Swarm fallback

[callexcapital]

Summary

• preserves dashboard-first Conductor dispatch when the dashboard mission API is available
• adds Workspace-native Swarm fallback for missing dashboard Conductor API with mode: native-swarm and modeOfficialOotb: true
• adds native mission status/cancel/readback handling and UI completion handling
• updates setup docs to provider-neutral / zero-fork native fallback wording
• adds regression coverage for native Conductor, Swarm dispatch/health/roster/profile, and gateway Conductor capability detection

Verification

• git diff --cached --check
• pnpm vitest run src/routes/api/-conductor-spawn.test.ts src/routes/api/-swarm-dispatch.test.ts src/routes/api/-swarm-health.test.ts src/server/swarm-memory.test.ts src/server/swarm-missions.test.ts src/server/swarm-profile-config.test.ts src/server/swarm-roster.test.ts src/server/__tests__/gateway-capabilities.test.ts — 44 passed
• pnpm exec eslint src/routes/api/conductor-spawn.ts src/routes/api/-conductor-spawn.test.ts src/routes/api/swarm-dispatch.ts src/routes/api/swarm-health.ts src/routes/api/swarm-missions.ts src/routes/api/swarm-runtime.ts src/routes/api/conductor-stop.ts src/server/swarm-memory.ts src/server/swarm-missions.ts src/server/swarm-profile-config.ts src/server/swarm-roster.ts src/server/gateway-capabilities.ts — 0 errors, 9 existing warnings
• pnpm build — passed

[outsourc-e]

Closing as superseded by #432. The validated fix was folded into the consolidated batch branch fix/issue-sweep-batch-20260514 for one review/merge path.