fix(quota): normalize OpenCode Go reset timestamps

Go returns ISO reset dates, but the shared usage contract requires numeric timestamps. Convert dates to milliseconds before building usage windows.

Verified all three windows against the live Go API. Added numeric timestamp and partial-window regressions; 14 focused tests, web type-check, lint, and syntax checks pass.

packages/web/server/lib/quota/providers/opencode-go.js

@@ -25,7 +25,7 @@ export const parseOpenCodeGoUsage = (payload) => {
     if (typeof resetAt !== 'string' || !Number.isFinite(new Date(resetAt).getTime())) continue;
     windows[key] = toUsageWindow({
       usedPercent: Math.min(100, Math.max(0, usedPercent)),
-      resetAt,
+      resetAt: new Date(resetAt).getTime(),
       windowSeconds: null,
     });
   }

packages/web/server/lib/quota/providers/opencode-go.test.js

@@ -27,11 +27,36 @@ describe('OpenCode Go quota provider', () => {
   it('parses partial API usage windows', () => {
     const windows = parseOpenCodeGoUsage({ usage: { rolling: { percent: 25, resetsAt: '2026-08-12T12:00:00.000Z' }, weekly: { percent: 40, resetsAt: '2026-08-19T12:00:00.000Z' } } });
     expect(windows['5h'].usedPercent).toBe(25);
-    expect(windows['5h'].resetAt).toBe('2026-08-12T12:00:00.000Z');
+    expect(windows['5h'].resetAt).toBe(Date.parse('2026-08-12T12:00:00.000Z'));
     expect(windows.weekly.usedPercent).toBe(40);
     expect(windows.monthly).toBeUndefined();
   });
 
+  it('returns numeric reset timestamps for all usage windows', async () => {
+    const resetsAt = '2026-10-01T00:00:00.000Z';
+    const windows = await fetchOpenCodeGoUsage('test-key', async () => new Response(JSON.stringify({
+      usage: {
+        rolling: { percent: 25, resetsAt },
+        weekly: { percent: 40, resetsAt },
+        monthly: { percent: 60, resetsAt },
+      },
+    })));
+    expect(Object.keys(windows)).toEqual(['5h', 'weekly', 'monthly']);
+    for (const window of Object.values(windows)) {
+      expect(window.resetAt).toBe(Date.parse(resetsAt));
+    }
+  });
+
+  it('preserves valid windows when another reset date is invalid', () => {
+    const windows = parseOpenCodeGoUsage({ usage: {
+      rolling: { percent: 25, resetsAt: 'invalid' },
+      weekly: { percent: 40, resetsAt: '2026-08-19T12:00:00.000Z' },
+      monthly: { percent: 60, resetsAt: null },
+    } });
+    expect(Object.keys(windows)).toEqual(['weekly']);
+    expect(windows.weekly.resetAt).toBe(Date.parse('2026-08-19T12:00:00.000Z'));
+  });
+
   it('does not expose credentials in authentication errors', async () => {
     await expect(fetchOpenCodeGoUsage('secret', async () => new Response('', { status: 403 }))).rejects.toThrow('authentication failed');
   });