feat(session-limits): LS4 — service application + réconciliation T4

Orchestre la détection et la reprise au niveau application :
- session_limit.rs (nouveau) : SessionLimitService + port AgentResumer +
  const RESUME_PROMPT.
- structured.rs : réconciliation T4 — enum TurnOutcome +
  drain_with_readiness_outcome ; signatures historiques préservées.
- agent/mod.rs + lib.rs : modules et re-exports.

Tests QA (nouveaux) : tests/session_limit_service.rs (9) +
tests/session_limit_t4.rs (7).
`cargo test -p application` = tous binaires verts / 0 failed (16 nouveaux),
zéro régression (drain_with_readiness_lot1 7/7, send_blocking_d1 9/9) ;
builds domaine+infra+application 0 warning.

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

crates/application/src/lib.rs

@@ -29,8 +29,9 @@ pub mod terminal;
 pub mod window;
 
 pub use agent::{
-    drain_with_readiness, reference_profile_id, reference_profiles, selectable_reference_profiles,
-    send_blocking, ChangeAgentProfile, ChangeAgentProfileInput, ChangeAgentProfileOutput,
+    drain_with_readiness, drain_with_readiness_outcome, reference_profile_id, reference_profiles,
+    selectable_reference_profiles, send_blocking, AgentResumer, ChangeAgentProfile,
+    ChangeAgentProfileInput, ChangeAgentProfileOutput,
     ConfigureProfiles, ConfigureProfilesInput, ConfigureProfilesOutput, CreateAgentFromScratch,
     CreateAgentInput, CreateAgentOutput, DeleteAgent, DeleteAgentInput, DeleteProfile,
     DeleteProfileInput, DetectProfiles, DetectProfilesInput, DetectProfilesOutput, FirstRunState,
@@ -41,8 +42,8 @@ pub use agent::{
     ProfileAvailability,
     ProviderSessionProvider, ReadAgentContext, ReadAgentContextInput, ReadAgentContextOutput,
     ReferenceProfiles, ReferenceProfilesOutput, ResumableAgent, SaveProfile, SaveProfileInput,
-    SaveProfileOutput, StructuredSessionDescriptor, UpdateAgentContext, UpdateAgentContextInput,
-    AGENT_MEMORY_RECALL_BUDGET,
+    SaveProfileOutput, SessionLimitService, StructuredSessionDescriptor, TurnOutcome,
+    UpdateAgentContext, UpdateAgentContextInput, AGENT_MEMORY_RECALL_BUDGET, RESUME_PROMPT,
 };
 pub use conversation::RecordTurn;
 pub use embedder::{