feat(ipc): SwitchLlm + ReloadLlm + QueryHealth — daemon hot-swap + state snapshot

Closes the "GUI shows GUI process state, not daemon's" gap. Now GUI can:
  1. Tell the daemon to swap LLM backend via IPC (so the running listener
     uses the new backend immediately, not just the GUI process).
  2. Tell the daemon to re-read llm_backend from settings DB after GUI persists
     a choice independently.
  3. Query the daemon's true runtime state (TTS/LLM/profile/memory/scheduler
     counts/language/version) for an honest footer + diagnostics view.

IpcAction (new variants)
  - SwitchLlm { backend: String }    — daemon calls llm::swap_to(parse(backend))
  - ReloadLlm                         — daemon calls llm::init_global() to re-read DB
  - QueryHealth                       — daemon responds with HealthSnapshot

IpcEvent (new variant)
  - HealthSnapshot { tts_backend, llm_backend, llm_model, active_profile,
                     memory_facts, scheduled_tasks, language, version }

jarvis-app main.rs
  - Imports IpcEvent (was only IpcAction before).
  - Three new match arms in ipc action handler — all use existing globals,
    no new state needed.

Next step (TODO): wire GUI's set_llm_backend Tauri command to ALSO fire
IpcAction::SwitchLlm so daemon stays in sync. And replace Footer.svelte's
get_active_backends call with QueryHealth over IPC.

Build: cargo build --release -p jarvis-app -p jarvis-gui green.
Tests: 62/62 pass (unchanged — IPC variants don't add testable logic).

crates/jarvis-core/src/ipc/events.rs

@@ -36,6 +36,18 @@ pub enum IpcEvent {
 
     // request GUI to reveal/focus window
     RevealWindow,
+
+    // Snapshot of daemon's runtime state (response to QueryHealth).
+    HealthSnapshot {
+        tts_backend: String,
+        llm_backend: String,
+        llm_model: Option<String>,
+        active_profile: String,
+        memory_facts: usize,
+        scheduled_tasks: usize,
+        language: String,
+        version: Option<String>,
+    },
 }
 
 // Actions sent from GUI to jarvis-app
@@ -56,4 +68,14 @@ pub enum IpcAction {
 
     // Execute text command
     TextCommand { text: String },
+
+    // Daemon-side LLM hot-swap (GUI's set_llm_backend should fire this too
+    // so the running daemon picks the new backend, not just the GUI process).
+    SwitchLlm { backend: String },
+
+    // Reload LLM backend from settings DB (after GUI changed it independently).
+    ReloadLlm,
+
+    // Request a health snapshot — daemon responds via IpcEvent::HealthSnapshot.
+    QueryHealth,
 }