feat: show the conversation evidence behind each learning trajectory

Reviewers were asked to include or exclude learning trajectories while
only seeing metadata — credit class, confidence, status. The decisions
and their redacted context turns were already captured and stored, but
no endpoint returned them, so the evidence was unreachable from the UI.

Add GET /api/learning/trajectories/:id and an expandable row on the
learning page that fetches on demand.

Also widen SentMessageSchema to accept matrixEventId, imageOutcomeCredit
and imageOutcomeAt. The learning loop added these to SentMessageRecord
and they flow out of /api/messages, but the strict contract rejected
them, breaking the dashboard.

Enable generation with shadow mode off so eligible examples reach reply
prompts.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/account-repositories.test.ts

@@ -134,6 +134,70 @@ describe('multi-account database ownership', () => {
     expect(db.pragma('foreign_key_check')).toEqual([]);
   });
 
+  it('removes an account with everything it owns and leaves other accounts intact', () => {
+    addAccount('t2_alice', 'alice-bot', 100);
+    addAccount('t2_bob', 'bob-bot', 110);
+
+    for (const accountId of ['t2_alice', 't2_bob']) {
+      db.prepare(`
+        INSERT INTO processed_posts (account_id, id, subreddit, author, title, processed_at)
+        VALUES (?, 'post-one', 'test', 'recipient', 'title', 1)
+      `).run(accountId);
+      db.prepare(`
+        INSERT INTO sent_messages (account_id, post_id, recipient, subject, message, sent_at)
+        VALUES (?, 'post-one', 'recipient', 'subject', 'message', 2)
+      `).run(accountId);
+      db.prepare(`
+        INSERT INTO successful_messages (account_id, original_message, created_at)
+        VALUES (?, 'message', 3)
+      `).run(accountId);
+      db.prepare(`
+        INSERT INTO delivery_outbox (
+          account_id, post_id, recipient, subject, message, idempotency_key,
+          status, created_at, updated_at
+        ) VALUES (?, 'post-one', 'recipient', 'subject', 'message', 'key', 'prepared', 1, 1)
+      `).run(accountId);
+      db.prepare(`
+        INSERT INTO activity_log (account_id, timestamp, type, message) VALUES (?, 4, 'sent', 'activity')
+      `).run(accountId);
+      db.prepare(`
+        INSERT INTO conversation_states (account_id, conversation_id, state_json, updated_at)
+        VALUES (?, 'room', '{}', 5)
+      `).run(accountId);
+      content.upsertConversation({
+        accountId, conversationId: 'room', username: 'recipient', roomName: 'Recipient',
+        payloadJson: '{}', updatedAt: 6,
+      });
+      content.saveSyncState({
+        accountId, nextBatch: 'cursor', lastFullSyncAt: 6, lastDeltaSyncAt: 6,
+        cooldownJson: null, updatedAt: 6,
+      });
+    }
+
+    expect(accounts.delete('t2_alice')).toBe(true);
+
+    expect(accounts.get('t2_alice')).toBeNull();
+    expect(accounts.listPublic().map((account) => account.accountId)).toContain('t2_bob');
+    for (const table of [
+      'processed_posts', 'sent_messages', 'successful_messages', 'delivery_outbox',
+      'activity_log', 'conversation_states', 'reddit_conversations', 'reddit_account_sync_state',
+    ]) {
+      expect({ table, ...db.prepare(`SELECT COUNT(*) count FROM ${table} WHERE account_id = ?`).get('t2_alice') as object })
+        .toEqual({ table, count: 0 });
+      expect({ table, ...db.prepare(`SELECT COUNT(*) count FROM ${table} WHERE account_id = ?`).get('t2_bob') as object })
+        .toEqual({ table, count: 1 });
+    }
+    expect(db.pragma('foreign_key_check')).toEqual([]);
+  });
+
+  it('reports an unknown account as not removed and rejects a blank id', () => {
+    addAccount('t2_alice', 'alice-bot', 100);
+
+    expect(accounts.delete('t2_missing')).toBe(false);
+    expect(() => accounts.delete('  ')).toThrow(/accountId/);
+    expect(accounts.get('t2_alice')).not.toBeNull();
+  });
+
   it('scopes legacy account-produced table uniqueness by account', () => {
     addAccount('t2_alice', 'alice-bot', 100);
     addAccount('t2_bob', 'bob-bot', 110);