feat(ai-session): add FlowPilot AI-powered troubleshooting sessions

Implements Phase 1 of the FlowPilot-First pivot — the core AI session
experience where engineers describe a problem and FlowPilot guides them
through structured diagnosis with selectable options, free-text escape
hatches, and auto-generated documentation on resolution.

Backend: AISession + AISessionStep models, FlowPilot Engine (LLM
orchestration with structured JSON output), Flow Matching Engine v1
(semantic + keyword + recency scoring), 8 API endpoints with auth,
rate limiting, and AI quota enforcement.

Frontend: Intake screen, conversational session view with sidebar,
step cards with options/actions/resolution suggestions, resolve/escalate
modals, documentation view with rating, session history integration,
and /pilot route with sidebar navigation.

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

frontend/src/components/flowpilot/ConfidenceIndicator.tsx

@@ -0,0 +1,44 @@
+import { cn } from '@/lib/utils'
+
+interface ConfidenceIndicatorProps {
+  tier: string
+  score: number
+  className?: string
+}
+
+const TIER_CONFIG = {
+  guided: {
+    color: 'bg-emerald-400',
+    label: 'Proven path',
+    description: 'FlowPilot is following a known resolution path with high confidence.',
+  },
+  exploring: {
+    color: 'bg-amber-400',
+    label: 'Investigating',
+    description: 'FlowPilot is narrowing down the issue based on your responses.',
+  },
+  discovery: {
+    color: 'bg-violet-400',
+    label: 'New territory',
+    description: 'FlowPilot is exploring this issue — your responses help build the knowledge base.',
+  },
+} as const
+
+export function ConfidenceIndicator({ tier, score, className }: ConfidenceIndicatorProps) {
+  const config = TIER_CONFIG[tier as keyof typeof TIER_CONFIG] ?? TIER_CONFIG.discovery
+
+  return (
+    <div className={cn('group relative inline-flex items-center gap-2', className)}>
+      <span className={cn('h-2 w-2 rounded-full', config.color)} />
+      <span className="font-label text-xs text-muted-foreground">{config.label}</span>
+
+      {/* Tooltip */}
+      <div className="pointer-events-none absolute left-0 top-full z-50 mt-2 w-56 rounded-lg border border-border bg-card p-3 opacity-0 shadow-lg transition-opacity group-hover:pointer-events-auto group-hover:opacity-100">
+        <p className="text-xs text-muted-foreground">{config.description}</p>
+        <p className="mt-1 font-label text-[0.625rem] text-[#5a6170]">
+          Confidence: {Math.round(score * 100)}%
+        </p>
+      </div>
+    </div>
+  )
+}