feat(desktop): re-snapshot persona config on every agent spawn

[wpfleger96]

Summary

When an agent linked to a persona is spawned (or auto-restored on launch), the persona's current system_prompt, model, provider, env_vars, and persona_source_version hash are written back onto the agent record before the process starts. This clears the "OUT OF DATE" drift badge without requiring a delete+recreate cycle.

Changes

commands/agents.rs — In start_local_agent_with_preflight, before calling start_managed_agent_process, re-snapshot the persona onto the mutable record. After save_managed_agents, call retain_managed_agent_pending to queue a relay publish of the updated record.

managed_agents/restore.rs — In restore_managed_agents_on_launch Phase A, after building to_start, re-snapshot all persona-linked agents in that set. Set changed = true so the refreshed records are persisted. Re-collect to_start from the mutated records slice so Phase B spawns the refreshed config.

ManagedAgentRow.tsx — Update the "OUT OF DATE" badge tooltip to remove the now-stale instruction to delete the agent before respawning.

Behavior

• Agent-level env_vars overrides still win — persona_snapshot layers persona env under agent overrides, matching the create-time contract.
• Agents without a persona_id are unaffected.
• If the linked persona is deleted, the agent spawns from its existing record fields (same fallback as before).

Acceptance Criteria

• After editing a persona's system prompt and clicking Spawn on a linked agent, the agent starts with the new system prompt and the "OUT OF DATE" badge is gone
• persona_source_version on the agent record matches the current persona hash after spawn
• Auto-start agents pick up the current persona on app launch
• cargo check passes clean