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/domain/src/lib.rs

@@ -47,6 +47,7 @@ pub mod orchestrator;
 pub mod ports;
 pub mod profile;
 pub mod project;
+pub mod readiness;
 pub mod remote;
 pub mod skill;
 pub mod template;
@@ -74,7 +75,8 @@ pub use skill::{Skill, SkillRef, SkillScope};
 pub use template::{AgentTemplate, TemplateVersion};
 
 pub use profile::{
-    AgentProfile, ContextInjection, EmbedderProfile, EmbedderStrategy, SessionStrategy,
+    AgentProfile, ContextInjection, EmbedderProfile, EmbedderStrategy, LivenessStrategy,
+    McpServerWiring, SessionStrategy,
 };
 
 pub use mailbox::{AgentMailbox, MailboxError, PendingReply, Ticket, TicketId};
@@ -84,7 +86,9 @@ pub use conversation::{
     ConversationSession, SessionRef, WaitForGraph,
 };
 
-pub use input::{AgentBusyState, InputMediator, InputSource};
+pub use input::{AgentBusyState, AgentLiveness, InputMediator, InputSource};
+
+pub use readiness::{ReadinessPolicy, ReadinessSignal};
 
 pub use conversation_log::{
     ConversationLog, ConversationTurn, Handoff, HandoffStore, HandoffSummarizer,