feat: ε-greedy v1 as active policy; dwell-time reward inference; offline sim framework

- Promote egreedy-v1 to active serving policy (ADR-0007): /score/egreedy + /reward/egreedy
  replaces linucb-v1 endpoints after offline sim shows +10.7% mean reward (−0.548 vs −0.606)
- Replace explicit helpful/not_helpful feedback with dwell-time inferred reward (inferReward):
  dismiss=−1.0, snooze=+0.1, done<15s=−0.3, done 15s–2min=+1.0, done 2–10min=+0.6, done>10min=+0.3
- Add ml/serving ε-greedy endpoints: /score/egreedy, /reward/egreedy, /stats/egreedy/{user_id}
  with d=7 feature vector (base 5 + sin/cos day-of-week encoding)
- Add offline simulation framework (ml/experiments/sim): rule/LLM/claude-code judges,
  two-phase score+reward, synthetic personas, task generator; results stored in sim_runs/sim_events
- Add /admin/simulations page: start runs, live-poll status, reward curve SVG, action/persona tables
- Fix egreedy day_of_week training skew: reward endpoint now uses actual dow instead of hardcoded 0
- Fix runner.py proxy bypass: httpx.Client(trust_env=False) for localhost ML calls
- Add dwellMs to TipFeedbackEvent contract and bus.test.ts fixture
- Schema: sim_runs, sim_events tables; tip_feedback gains dwell_ms, reward_milli columns
- ADR-0006: admin console framework; ADR-0007: egreedy-v1 policy selection rationale

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

services/api/src/db/index.ts

@@ -99,6 +99,40 @@ export function runMigrations() {
       sql TEXT NOT NULL,
       created_at TEXT NOT NULL
     );
+
+    CREATE TABLE IF NOT EXISTS sim_runs (
+      id TEXT PRIMARY KEY,
+      policy_a TEXT NOT NULL,
+      policy_b TEXT NOT NULL,
+      n_users INTEGER NOT NULL,
+      n_rounds INTEGER NOT NULL,
+      tasks_per_round INTEGER NOT NULL DEFAULT 8,
+      use_llm INTEGER NOT NULL DEFAULT 0,
+      status TEXT NOT NULL DEFAULT 'pending',
+      summary_json TEXT,
+      winner TEXT,
+      persona_breakdown_json TEXT,
+      created_at TEXT NOT NULL,
+      finished_at TEXT
+    );
+
+    CREATE TABLE IF NOT EXISTS sim_events (
+      id TEXT PRIMARY KEY,
+      run_id TEXT NOT NULL REFERENCES sim_runs(id),
+      round INTEGER NOT NULL,
+      user_id TEXT NOT NULL,
+      persona TEXT NOT NULL,
+      policy TEXT NOT NULL,
+      tip_content TEXT NOT NULL,
+      priority INTEGER NOT NULL,
+      is_overdue INTEGER NOT NULL,
+      action TEXT NOT NULL,
+      dwell_ms INTEGER,
+      reward_milli INTEGER NOT NULL,
+      hour INTEGER NOT NULL,
+      day_of_week INTEGER NOT NULL,
+      created_at TEXT NOT NULL
+    );
   `);
 
   // Additive column migrations — safe to run on existing DBs.
@@ -106,6 +140,8 @@ export function runMigrations() {
   for (const stmt of [
     `ALTER TABLE users ADD COLUMN role TEXT NOT NULL DEFAULT 'user'`,
     `ALTER TABLE push_subscriptions ADD COLUMN created_at TEXT NOT NULL DEFAULT ''`,
+    `ALTER TABLE tip_feedback ADD COLUMN dwell_ms INTEGER`,
+    `ALTER TABLE tip_feedback ADD COLUMN reward_milli INTEGER`,
   ]) {
     try { sqlite.exec(stmt); } catch { /* column already exists */ }
   }