feat(phase6b): LLM analysis layer — DeepSeek + insights + cost ledger + budget guard

Schema:
- insights (fingerprint dedup, occurrence_count, related_session_ids[], priority_score)
- cost_ledger (per-call, cache_hit/miss/output token split + USD)
- prompt_templates (versioned, per-tag, with JSON schema + tier + temperature)
- budget_settings (global key/value: monthly_hard_cap_usd, daily_soft/hard, per_call_max, analysis_paused)

Worker:
- lib/deepseek.ts: Anthropic-compat endpoint client (deepseek-v4-flash | deepseek-v4-pro),
  usage→USD with V4 promo pricing, cache_read_input_tokens awareness, extractJson() helper
- lib/budget.ts: checkBudget() returns active|soft_throttled|hard_paused|monthly_paused,
  forces flash tier on soft cap, halts on hard/monthly cap or analysis_paused
- lib/prompts.ts: 5 seed templates (bug_triage P, ux_friction F, payment_issue P,
  onboarding_stuck F, provider_quality F) with embedded JSON schemas + Sase.tr context;
  pickPromptTag() maps session tags → prompt
- lib/json-validate.ts: lightweight schema validator (no ajv dep)
- lib/seed-runtime.ts: idempotent upsert of prompts + default budget settings on worker boot
- lib/minio.ts: +getText() for compressed timeline fetch
- jobs/analyze.ts: budget guard → 6h fingerprint cache (attach session to existing insight) →
  template lookup → severity-based tier override → DeepSeek call → JSON parse + validate →
  insert insight (or aggregate occurrence) → write cost_ledger
- scheduler: analyze@*/4min on insight-pipeline queue

UI:
- /insights (was pipeline view) → now Insight Inbox: priority-sorted list w/ KPI strip
  (new/in_backlog/shipped/today $/month $), severity badges, link to detail
- /insights/i/[id]: insight detail with structured body render, related sessions,
  per-session cost breakdown, raw JSON collapsible
- /insights/costs: KPI cards (today, month, avg, cache hit), daily 30d bar table,
  by-model + by-prompt breakdowns, top 10 expensive, recent errors
- /insights/pipeline: moved old session-pipeline view here
- /insights/sessions/[id]: unchanged session timeline viewer

Defaults:
- monthly cap $30, daily soft $1.50 / hard $3, per-call $0.20, analysis_paused=false
- Severity→Tier: P0/P1=pro, P2/P3/INFO=flash; budget soft-cap forces flash

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/web/prisma/schema.prisma

@@ -217,3 +217,108 @@ model SessionCustomEvent {
   @@index([sessionId, timestamp])
   @@map("session_custom_events")
 }
+
+// ---------- Phase 6b: LLM Analysis ----------
+
+model PromptTemplate {
+  id                 String   @id @default(cuid())
+  tag                String
+  version            Int
+  name               String
+  systemPrompt       String   @db.Text
+  userPromptTemplate String   @db.Text
+  outputSchemaJson   Json
+  modelTier          String   // "flash" | "pro"
+  maxOutputTokens    Int      @default(1500)
+  temperature        Float    @default(0.3)
+  active             Boolean  @default(true)
+  performanceStats   Json     @default("{}")
+  createdAt          DateTime @default(now())
+  updatedAt          DateTime @updatedAt
+
+  @@unique([tag, version])
+  @@map("prompt_templates")
+}
+
+model Insight {
+  id                    String    @id @default(cuid())
+  projectKey            String
+  type                  String
+  severity              String
+  status                String    @default("new")
+  fingerprint           String
+  title                 String
+  body                  Json
+  relatedSessionIds     String[]
+  occurrenceCount       Int       @default(1)
+  uniqueUserCount       Int       @default(1)
+  firstSeenAt           DateTime
+  lastSeenAt            DateTime
+  confidence            Float?
+  priorityScore         Int       @default(0)
+  sourcePromptTag       String
+  sourcePromptVersion   Int
+  sourceModel           String
+  sourceCostUsd         Float
+  githubIssueUrl        String?
+  githubIssueId         BigInt?
+  githubIssueState      String?
+  shippedAt             DateTime?
+  validationStartedAt   DateTime?
+  validationPeriodDays  Int       @default(14)
+  regressionDetected    Boolean   @default(false)
+  validatedAt           DateTime?
+  founderNotes          String?   @db.Text
+  founderSeverityOverride String?
+  founderPriority       Int?
+  createdAt             DateTime  @default(now())
+  updatedAt             DateTime  @updatedAt
+
+  @@unique([projectKey, fingerprint])
+  @@index([status, projectKey])
+  @@index([severity, status])
+  @@index([lastSeenAt(sort: Desc)])
+  @@index([priorityScore(sort: Desc)])
+  @@map("insights")
+}
+
+model CostLedger {
+  id                       String   @id @default(cuid())
+  insightId                String?
+  sessionId                String?
+  projectKey               String
+  promptTag                String?
+  promptVersion            Int?
+  provider                 String   // "deepseek" | "anthropic" | "openrouter"
+  model                    String
+  tier                     String   // "flash" | "pro"
+  tokensInputCacheMiss     Int
+  tokensInputCacheHit      Int
+  tokensOutput             Int
+  costInputCacheMissUsd    Float
+  costInputCacheHitUsd     Float
+  costOutputUsd            Float
+  costTotalUsd             Float
+  cacheHitRatio            Float
+  callDurationMs           Int?
+  wasFallback              Boolean  @default(false)
+  wasRetry                 Boolean  @default(false)
+  errorCode                String?
+  createdAt                DateTime @default(now())
+
+  @@index([createdAt])
+  @@index([projectKey, createdAt])
+  @@index([insightId])
+  @@map("cost_ledger")
+}
+
+model BudgetSetting {
+  id            String   @id @default(cuid())
+  projectKey    String?  // null = global
+  settingKey    String
+  settingValue  Json
+  updatedAt     DateTime @updatedAt
+
+  @@unique([projectKey, settingKey])
+  @@map("budget_settings")
+}