feat(ai-session): add Phase 2 PSA integration, escalation handoff, and session management

Phase 2 of the FlowPilot-First Pivot connecting AI sessions to ConnectWise PSA:

Slice 1 — PSA Ticket Intake:
- FlowPilotEngine accepts psa_ticket intake with graceful CW API fallback
- Ticket picker on intake screen (refactored TicketPickerModal for dual-mode)
- Ticket context card in session sidebar

Slice 2 — Auto Documentation Push:
- PSA documentation service with resolution/escalation note formatting
- Time entry creation via new ConnectWise provider method
- Automatic retry scheduler (APScheduler, 5min interval, 3 retries)
- PSA push status indicators in frontend with manual retry button
- Member mapping warning when CW member not mapped

Slice 3 — Session Pause/Resume & Escalation Handoff:
- Pause/resume endpoints for same-engineer session bookmarking
- Escalation flow: requesting_escalation status, self-escalation blocked
- Enhanced escalation package with LLM-generated hypotheses/suggestions
- Pickup endpoint with continue/fresh resume modes and briefing step
- Escalation queue (sidebar nav + dedicated page)
- SessionBriefing component with continue/fresh choice UI
- EscalateModal with PSA-aware button text

Slice 4 — Mid-Session Ticket Linking:
- Link ticket retroactively with context injection into system prompt
- Link Ticket button in session sidebar

Slice 5 — FlowPilot PSA Settings:
- Settings tab on IntegrationsPage with 7 configurable options
- Stored as flowpilot_settings JSONB on PsaConnection

Database: 2 migrations (flowpilot_settings, psa_post_log changes, status constraint)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/services/psa_retry_scheduler.py

@@ -0,0 +1,52 @@
+"""Background scheduler for retrying failed PSA documentation pushes.
+
+Runs every 5 minutes via APScheduler, picks up PsaPostLog entries
+with status='pending_retry' and next_retry_at <= now.
+"""
+import logging
+from datetime import datetime, timezone
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.database import async_session_maker
+from app.models.psa_post_log import PsaPostLog
+from app.services.psa_documentation_service import retry_failed_push
+
+logger = logging.getLogger(__name__)
+
+
+async def process_pending_retries() -> None:
+    """Process all pending PSA push retries that are due."""
+    async with async_session_maker() as db:
+        try:
+            result = await db.execute(
+                select(PsaPostLog)
+                .where(
+                    PsaPostLog.status == "pending_retry",
+                    PsaPostLog.next_retry_at <= datetime.now(timezone.utc),
+                    PsaPostLog.retry_count < 3,
+                )
+                .limit(20)  # Process in batches
+            )
+            entries = result.scalars().all()
+
+            if not entries:
+                return
+
+            logger.info("Processing %d pending PSA push retries", len(entries))
+
+            for entry in entries:
+                success = await retry_failed_push(entry, db)
+                if success:
+                    logger.info("PSA retry succeeded for log %s", entry.id)
+                else:
+                    logger.warning(
+                        "PSA retry %d/%d failed for log %s",
+                        entry.retry_count, 3, entry.id,
+                    )
+
+            await db.commit()
+        except Exception as e:
+            logger.error("PSA retry scheduler error: %s", e)
+            await db.rollback()