0.5.0: TTL expiration, reconnect hardening, and agent telemetry

[AdityaVG13]

Summary

• add TTL/hard-expiration support for memories/decisions (schema + store + recall + compaction)
• harden daemon/MCP reconnect behavior for mid-session restarts (longer health waits, unlimited respawn attempts with cooldown, session re-registration)
• improve Control Center startup/stop smoothness and clarify boot-savings analytics with richer per-agent visibility
• track agent presence/model labels in sessions so AGENTS shows active model identities (e.g. DROID (5.3 Codex Extra High))

Validation

• rtk cargo test (daemon-rs): 84 passed
• rtk cargo clippy -- --deny warnings
• npm --prefix desktop/cortex-control-center run test: 24 passed
• npm --prefix desktop/cortex-control-center run web:build
• cargo check (desktop/cortex-control-center/src-tauri)