feat(agents): pont Codex inter-agents + readiness/heartbeat lot 1

Deux chantiers livrés au vert (workspace entier : domain+application+
infrastructure 42 + app-tauri --lib 128, 0 échec).

## Codex inter-agents
- domaine: McpConfigStrategy::TomlConfigHome { target, home_env } +
  toml_config_home(...); AgentProfile::materializes_idea_bridge()
  (whitelist Claude/ConfigFile + Codex/TomlConfigHome); McpServerWiring
  + encodeur TOML.
- application: lifecycle apply_mcp_config bras TomlConfigHome (écrit
  {runDir}/<target>, pousse (home_env, parent) dans spec.env);
  guard_mcp_bridge_supported ré-exprimée via materializes_idea_bridge();
  catalogue Codex porte toml_config_home(".codex/config.toml","CODEX_HOME").
- app-tauri: is_codex_mcp_profile, migrate_codex_run_dir,
  mcp_server_entry_toml.
- tests: matrice domaine TomlConfigHome + round-trip dual Claude/Codex
  sur loopback réel (fakes, zéro token).

## Readiness/heartbeat lot 1
- domaine: readiness.rs — ReadinessPolicy::classify (Final => TurnEnded),
  variantes ReplyEvent::Heartbeat / ToolActivity.
- application: drain_with_readiness consulte la policy et appelle
  mark_idle sur le signal déterministe; branché dans ask_agent.
  Corrige la cause racine: une cible qui ne renvoie qu'un Final (sans
  idea_reply) débloque désormais sa file Busy.
- infrastructure: adapters de session émettent Heartbeat/ToolActivity.
- tests: drain_with_readiness_lot1 (points QA 5 & 6) verts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/app-tauri/tests/chat_bridge.rs

@@ -57,7 +57,7 @@ fn final_chunk(s: &str) -> ReplyChunk {
 fn chunk_from_event_maps_text_delta() {
     assert_eq!(
         chunk_from_event(ReplyEvent::TextDelta { text: "hi".into() }),
-        ReplyChunk::TextDelta { text: "hi".into() }
+        Some(ReplyChunk::TextDelta { text: "hi".into() })
     );
 }
 
@@ -67,9 +67,9 @@ fn chunk_from_event_maps_tool_activity() {
         chunk_from_event(ReplyEvent::ToolActivity {
             label: "reads file".into()
         }),
-        ReplyChunk::ToolActivity {
+        Some(ReplyChunk::ToolActivity {
             label: "reads file".into()
-        }
+        })
     );
 }
 
@@ -79,12 +79,19 @@ fn chunk_from_event_maps_final() {
         chunk_from_event(ReplyEvent::Final {
             content: "done".into()
         }),
-        ReplyChunk::Final {
+        Some(ReplyChunk::Final {
             content: "done".into()
-        }
+        })
     );
 }
 
+#[test]
+fn chunk_from_event_drops_heartbeat() {
+    // A heartbeat is a non-terminal liveness proof with no chat content (lot 1) ⇒ no
+    // wire chunk; the pump skips it while still draining to the Final.
+    assert_eq!(chunk_from_event(ReplyEvent::Heartbeat), None);
+}
+
 // ---------------------------------------------------------------------------
 // agent_send pump behaviour: deltas* then exactly one Final (zone 2)
 // ---------------------------------------------------------------------------
@@ -94,7 +101,10 @@ fn chunk_from_event_maps_final() {
 /// end. This is the body of the spawned pump thread, run inline.
 fn pump_turn(bridge: &ChatBridge, session: &SessionId, gen: u64, events: Vec<ReplyEvent>) {
     for event in events {
-        let _ = bridge.send_output(session, chunk_from_event(event));
+        // Mirror the real pump: heartbeats map to no chunk and are skipped.
+        if let Some(chunk) = chunk_from_event(event) {
+            let _ = bridge.send_output(session, chunk);
+        }
     }
     bridge.detach_if(session, gen);
 }