feat: add cockpit triage backend foundation (Phase 1)

- Migration 071: add client_name, asset_name, issue_category,
  triage_hypothesis, evidence_items columns to ai_sessions
- TriageUpdate schema for AI-inferred header updates in chat responses
- QuestionItem.options field for quick-reply buttons
- PATCH /ai-sessions/{id}/triage endpoint for manual header edits
- POST /ai-sessions/{id}/handoff-draft streaming endpoint for conclude modal
- Structured handoff fields (root_cause, steps_taken, recommendations)
  on resolve/escalate requests, passed through to ResolutionOutputGenerator
- Triage fields exposed in AISessionDetail response for session resume

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/services/resolution_output_generator.py

@@ -19,7 +19,13 @@ class ResolutionOutputGenerator:
     def __init__(self, db: AsyncSession):
         self.db = db
 
-    async def generate_all(self, session_id: UUID) -> list[SessionResolutionOutput]:
+    async def generate_all(
+        self,
+        session_id: UUID,
+        root_cause: str | None = None,
+        steps_taken: list[str] | None = None,
+        recommendations: str | None = None,
+    ) -> list[SessionResolutionOutput]:
         result = await self.db.execute(
             select(AISession).where(AISession.id == session_id)
         )
@@ -27,7 +33,12 @@ class ResolutionOutputGenerator:
         if not session:
             raise ValueError(f"Session {session_id} not found")
 
-        context = self._build_session_context(session)
+        context = self._build_session_context(
+            session,
+            root_cause=root_cause,
+            steps_taken=steps_taken,
+            recommendations=recommendations,
+        )
 
         outputs = []
         for output_type, prompt in [
@@ -82,13 +93,41 @@ class ResolutionOutputGenerator:
         await self.db.flush()
         return output
 
-    def _build_session_context(self, session: AISession) -> str:
+    def _build_session_context(
+        self,
+        session: AISession,
+        root_cause: str | None = None,
+        steps_taken: list[str] | None = None,
+        recommendations: str | None = None,
+    ) -> str:
         parts = [
             f"Problem: {session.problem_summary or 'Unknown'}",
             f"Domain: {session.problem_domain or 'Unknown'}",
             f"Resolution: {session.resolution_summary or 'Not specified'}",
             f"Steps taken: {session.step_count}",
         ]
+
+        # Structured handoff fields from cockpit conclude modal
+        if root_cause:
+            parts.append(f"Root cause: {root_cause}")
+        if steps_taken:
+            parts.append("Steps performed:")
+            for step in steps_taken:
+                parts.append(f"  - {step}")
+        if recommendations:
+            parts.append(f"Recommendations: {recommendations}")
+
+        # Triage metadata
+        if getattr(session, 'client_name', None):
+            parts.append(f"Client: {session.client_name}")
+        if getattr(session, 'triage_hypothesis', None):
+            parts.append(f"Hypothesis: {session.triage_hypothesis}")
+        if getattr(session, 'evidence_items', None):
+            parts.append("Evidence collected:")
+            for item in session.evidence_items:
+                icon = {"confirmed": "✓", "ruled_out": "✗", "pending": "?"}.get(item.get("status", ""), "?")
+                parts.append(f"  {icon} {item.get('text', '')}")
+
         msgs = session.conversation_messages or []
         if msgs:
             parts.append("\nConversation highlights:")