feat(chat): propage l'intention chat → require_structured dans le pipeline de lancement

- Ajoute le champ cell_kind dans LaunchAgentRequestDto pour distinguer les demandes chat (custom CLI) des lancements PTY historiques
- Convertit cellKind:Chat en require_structured:true dans commands.rs et web-server/src/lib.rs
- Implémente la logique de routing structuré dans LaunchAgent::execute :
  - valide que require_structured implique un profil avec structured_adapter
  - remplace une session PTY existante quand require_structured est vrai
  - route vers structured seulement quand wants_structured est vrai
- Met à jour tous les appels historiques avec require_structured:false pour préserver le contrat PTY
- Ajoute les tests unitaires human_launcher_with_chat_intent_routes_structured_profile_to_chat_session et chat_intent_replaces_existing_pty_instead_of_returning_pty_session
- Wire les ports structured dans BackendCore pour le launcher humain

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

crates/application/src/agent/lifecycle.rs

@@ -959,6 +959,7 @@ impl ChangeAgentProfile {
                 // endpoint is re-driven through the app-tauri launch path.
                 mcp_runtime: None,
                 allow_structured_alongside_pty: false,
+                require_structured: false,
             })
             .await?;
         Ok(Some(output.session))
@@ -1112,6 +1113,12 @@ pub struct LaunchAgentInput {
     ///
     /// Ordinary UI launches keep this `false` and retain the singleton/rebind guard.
     pub allow_structured_alongside_pty: bool,
+    /// UI routing intent for the custom chat CLI: when `true`, a profile carrying a
+    /// `structured_adapter` must be launched as an [`AgentSession`] even on the
+    /// human-facing launcher, instead of taking the native TUI/PTY fallback.
+    ///
+    /// Historical callers leave this `false`, preserving the PTY launch contract.
+    pub require_structured: bool,
 }
 
 /// OS/runtime facts injected by the composition root (`app-tauri`) to materialise
@@ -1813,6 +1820,25 @@ impl LaunchAgent {
         let agent = entry
             .to_agent()
             .map_err(|e| AppError::Invalid(e.to_string()))?;
+        let mut profile = self
+            .profiles
+            .list()
+            .await?
+            .into_iter()
+            .find(|p| p.id == agent.profile_id)
+            .ok_or_else(|| AppError::NotFound(format!("profile {} for agent", agent.profile_id)))?;
+        if input.require_structured && profile.structured_adapter.is_none() {
+            return Err(AppError::Invalid(format!(
+                "agent {}: le lancement structuré a été demandé, mais le profil {} \
+                 ne déclare pas d'adaptateur structured/headless",
+                input.agent_id, profile.id
+            )));
+        }
+        let wants_structured = input.require_structured
+            || matches!(
+                self.structured_routing_mode,
+                StructuredRoutingMode::RequireStructured
+            );
 
         // 1b. Enforce the "one live session per agent" invariant (decision: an
         //     agent is a singleton that runs in a single cell at a time). This
@@ -1847,12 +1873,16 @@ impl LaunchAgent {
             let host_node = self
                 .sessions
                 .node_for_agent_in_project(input.project.id, &input.agent_id);
-            if input.allow_structured_alongside_pty && input.node_id.is_none() {
+            if input.allow_structured_alongside_pty && input.node_id.is_none() && wants_structured {
                 crate::diag!(
                     "[launch] existing PTY kept while structured launch proceeds: agent={} \
                      pty_session={existing_id}",
                     input.agent_id
                 );
+            } else if input.require_structured && profile.structured_adapter.is_some() {
+                if let Some(handle) = self.sessions.remove(&existing_id) {
+                    self.pty.kill(&handle).await?;
+                }
             } else {
                 match reattach_decision(input.node_id, host_node, input.conversation_id.as_deref())
                 {
@@ -1947,13 +1977,6 @@ impl LaunchAgent {
             .contexts
             .read_context(&input.project, &agent.id)
             .await?;
-        let mut profile = self
-            .profiles
-            .list()
-            .await?
-            .into_iter()
-            .find(|p| p.id == agent.profile_id)
-            .ok_or_else(|| AppError::NotFound(format!("profile {} for agent", agent.profile_id)))?;
         if input.allow_structured_alongside_pty && profile.structured_adapter.is_none() {
             return Err(AppError::Invalid(format!(
                 "agent {}: le lancement headless structuré a été demandé, mais le profil {} \
@@ -2109,10 +2132,10 @@ impl LaunchAgent {
             profile.structured_adapter.is_some(),
             self.session_factory.as_ref(),
             self.structured.as_ref(),
-            self.structured_routing_mode,
+            wants_structured,
         ) {
             (false, _, _, _) => {}
-            (true, Some(factory), Some(structured), _) => {
+            (true, Some(factory), Some(structured), true) => {
                 // ── Clé **logique** de la cellule = id de paire IdeA (ARCHITECTURE §19.7,
                 //    lot P8a) ──
                 //  - cellule porteuse d'un `conversation_id` (resume, ou lancement délégué
@@ -2152,10 +2175,10 @@ impl LaunchAgent {
                     )
                     .await;
             }
-            (true, _, _, StructuredRoutingMode::HumanPtyFallback) => {
+            (true, _, _, false) => {
                 // Fallback humain intentionnel : cellule interactive native en PTY.
             }
-            (true, _, _, StructuredRoutingMode::RequireStructured) => {
+            (true, _, _, true) => {
                 return Err(AppError::Process(
                     "structured profile requires structured session factory".to_owned(),
                 ));