feat(observability): structured logs, W3C trace IDs, Sentry hooks (#18)

- TS: pino + pino-http; every HTTP request log includes traceId from
  W3C traceparent header (generated if absent); forwarded to ml/serving
  on all /score, /generate, /reward, and /api/ml proxy calls
- Python: structlog JSON; FastAPI middleware binds trace_id via
  contextvars so every log line within a request carries it
- Sentry: optional SENTRY_DSN init in both runtimes (no-op if unset)
- Replace all console.* calls across services/api with pino logger
- Update tests to spy on logger instead of console

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

services/api/src/signals/__tests__/scheduler.test.ts

@@ -8,6 +8,11 @@
  */
 import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
 
+vi.mock('../../logger.js', () => ({
+  logger: { info: vi.fn(), warn: vi.fn(), error: vi.fn(), fatal: vi.fn() },
+}));
+import { logger } from '../../logger.js';
+
 // ── mock the drizzle query chain: db.select(...).from(...).where(...) ────────
 let users: { userId: string }[] = [];
 const whereMock = vi.fn(async () => users);
@@ -35,6 +40,7 @@ beforeEach(() => {
   whereMock.mockClear();
   fromMock.mockClear();
   selectMock.mockClear();
+  vi.clearAllMocks();
   vi.useFakeTimers();
 });
 
@@ -102,8 +108,6 @@ describe('startTodoistSyncScheduler', () => {
       if (id === 'bad') throw new Error('todoist 401');
       return [];
     });
-    const errSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
-    const logSpy = vi.spyOn(console, 'log').mockImplementation(() => {});
 
     startTodoistSyncScheduler(60_000);
     await vi.advanceTimersByTimeAsync(10_001);
@@ -112,19 +116,27 @@ describe('startTodoistSyncScheduler', () => {
     await Promise.resolve();
 
     expect(fetchSignalsMock).toHaveBeenCalledTimes(3);
-    expect(errSpy).toHaveBeenCalledWith(expect.stringContaining('sync error'), expect.anything());
-    expect(logSpy).toHaveBeenCalledWith(expect.stringContaining('2 ok, 1 failed'));
+    expect(logger.error).toHaveBeenCalledWith(
+      expect.objectContaining({ err: expect.anything() }),
+      'scheduler: sync error',
+    );
+    expect(logger.info).toHaveBeenCalledWith(
+      expect.objectContaining({ ok: 2, failed: 1 }),
+      'scheduler: todoist sync',
+    );
   });
 
   it('survives a db query failure — logs and skips the tick', async () => {
     const { startTodoistSyncScheduler } = await import('../scheduler.js');
     whereMock.mockRejectedValueOnce(new Error('sqlite locked'));
-    const errSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
 
     startTodoistSyncScheduler(60_000);
     await vi.advanceTimersByTimeAsync(10_001);
 
     expect(fetchSignalsMock).not.toHaveBeenCalled();
-    expect(errSpy).toHaveBeenCalledWith(expect.stringContaining('failed to query users'));
+    expect(logger.error).toHaveBeenCalledWith(
+      expect.objectContaining({ err: expect.anything() }),
+      'scheduler: failed to query users',
+    );
   });
 });

services/api/src/signals/aggregator.ts

@@ -1,4 +1,5 @@
 import type { Signal, SignalSource } from '@oo/shared-types';
+import { logger } from '../logger.js';
 
 /**
  * Merges signals from all registered sources for a user.
@@ -24,7 +25,7 @@ export class SignalAggregator {
       if (r.status === 'fulfilled') {
         signals.push(...r.value);
       } else {
-        console.error(`[aggregator] source '${this.sources[i].id}' failed:`, r.reason);
+        logger.error({ sourceId: this.sources[i]!.id, err: r.reason }, 'aggregator: source failed');
       }
     }
     return signals;

services/api/src/signals/scheduler.ts

@@ -13,6 +13,7 @@ import { db } from '../db/index.js';
 import { integrationTokens } from '../db/schema.js';
 import { eq } from 'drizzle-orm';
 import { todoistSource } from './todoist.js';
+import { logger } from '../logger.js';
 
 const DEFAULT_INTERVAL_MS = 15 * 60 * 1000;
 
@@ -25,7 +26,7 @@ export function startTodoistSyncScheduler(intervalMs = DEFAULT_INTERVAL_MS): Nod
         .from(integrationTokens)
         .where(eq(integrationTokens.tokenStatus, 'active'));
     } catch (err: any) {
-      console.error(`[scheduler] failed to query users: ${err.message}`);
+      logger.error({ err }, 'scheduler: failed to query users');
       return;
     }
 
@@ -39,10 +40,10 @@ export function startTodoistSyncScheduler(intervalMs = DEFAULT_INTERVAL_MS): Nod
     let failed = 0;
     for (const r of results) {
       if (r.status === 'fulfilled') ok++;
-      else { failed++; console.error(`[scheduler] sync error:`, r.reason); }
+      else { failed++; logger.error({ err: r.reason }, 'scheduler: sync error'); }
     }
 
-    console.log(`[scheduler] todoist sync: ${ok} ok, ${failed} failed (${users.length} users)`);
+    logger.info({ ok, failed, total: users.length }, 'scheduler: todoist sync');
   }
 
   // Run once shortly after startup, then on interval

services/api/src/signals/todoist.ts

@@ -3,6 +3,7 @@ import { db } from '../db/index.js';
 import { integrationTokens } from '../db/schema.js';
 import { eq, and } from 'drizzle-orm';
 import { bus } from '../events/bus.js';
+import { logger } from '../logger.js';
 
 const CACHE_TTL_MS = 30_000;
 
@@ -46,7 +47,7 @@ export class TodoistSignalSource implements SignalSource {
 
     if (!res.ok) {
       if (res.status === 401) {
-        console.error(`[todoist] token expired for user ${userId}`);
+        logger.warn({ userId }, 'todoist: token expired');
         bus.publish('signals.integration.token_expired', {
           userId,
           provider: 'todoist',