Fix agent registry name preservation with SQLite

[codeaholicguy]

Summary

• Replace the JSON-backed live agent registry with a SQLite-backed registry keyed by provider type and PID.
• Preserve user-managed agent names and tmux session metadata when adapter polling emits generated fallback names.
• Import legacy agents.json entries into SQLite with same-PID dedupe and add lifecycle docs for the change.

Validation

• npm test --workspace @ai-devkit/agent-manager -- AgentRegistry.test.ts AgentManager.test.ts CodexAdapter.test.ts GeminiCliAdapter.test.ts PiAdapter.test.ts CopilotAdapter.test.ts PrintAgentStore.test.ts
• npm test --workspace ai-devkit -- agent.service.test.ts agent.test.ts
• npm run typecheck --workspace @ai-devkit/agent-manager
• npm run build --workspace @ai-devkit/agent-manager
• npm run lint --workspace @ai-devkit/agent-manager
• npm run lint --workspace ai-devkit (passes with existing warnings)
• npx ai-devkit@latest lint --feature agent-registry-sqlite
• npx ai-devkit@latest lint

Notes

• Full agent-manager test suite is blocked in this sandbox by unrelated ClaudePrintAgent.integration.test.ts because local ps process identity lookup is denied.