feat(domain): live-state agent — modèle + port (LS1)

Domaine pur du live-state des agents : `LiveState`/`LiveEntry`/`WorkStatus`.
- Fusion en keyed last-writer-wins : une entrée par clé, la plus récente
  écrase l'ancienne (ordonnancement déterministe).
- Invariants de bornes anti-dump : bornes douces (troncature) + rejet dur
  au-delà des limites, pour empêcher un agent de noyer le live-state.
- `prune` pour borner la rétention.
- Port `LiveStateStore` (lecture/écriture), sans dépendance d'infra.

9 nouveaux tests live_state (cargo test -p domain : 208 passed / 0 failed).

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

crates/domain/src/lib.rs

@@ -40,6 +40,7 @@ pub mod git;
 pub mod ids;
 pub mod input;
 pub mod layout;
+pub mod live_state;
 pub mod mailbox;
 pub mod markdown;
 pub mod memory;
@@ -95,6 +96,8 @@ pub use conversation::{
 
 pub use input::{AgentBusyState, AgentLiveness, InputMediator, InputSource};
 
+pub use live_state::{LiveEntry, LiveState, WorkStatus, FIELD_MAX_BYTES, FIELD_PREVIEW_MAX_CHARS};
+
 pub use readiness::{ReadinessPolicy, ReadinessSignal};
 
 pub use session_limit::{plan_resume, RateLimitSource, ResumePlan, SessionLimit};
@@ -152,8 +155,8 @@ pub use ports::{
     EmbedderEnvInspector, EmbedderEnvReport, EmbedderError, EmbedderProfileStore,
     EmbedderPromptDismissal, EmbedderPromptStore, EventBus, EventStream, ExitStatus, FileSystem,
     FsError, GitCommitInfo, GitError, GitFileStatus, GitPort, GraphCommit, IdGenerator,
-    MemoryError, MemoryQuery, MemoryRecall, MemoryStore, Output, OutputStream, PermissionStore,
-    PreparedContext, ProcessError, ProcessSpawner, ProfileStore, ProjectStore, PtyError, PtyHandle,
-    PtyPort, RemoteError, RemoteHost, RemotePath, RuntimeError, ScheduledTask, Scheduler,
-    SpawnSpec, StoreError, TemplateStore,
+    LiveStateStore, MemoryError, MemoryQuery, MemoryRecall, MemoryStore, Output, OutputStream,
+    PermissionStore, PreparedContext, ProcessError, ProcessSpawner, ProfileStore, ProjectStore,
+    PtyError, PtyHandle, PtyPort, RemoteError, RemoteHost, RemotePath, RuntimeError, ScheduledTask,
+    Scheduler, SpawnSpec, StoreError, TemplateStore,
 };