admin: read/unread triage for load errors (unread by default, mark read/all)

The load-error log had no way to clear reviewed entries. Add a read_at column to
client_errors and a read/unread model mirroring the feedback inbox:
- GET /api/admin/client-errors?show=unread|read|all (default unread; returns id+read)
- POST /api/admin/client-errors/read-all  (mark all unread read)
- POST /api/admin/client-errors/{id}/read {read: bool}  (per-row toggle)
Headline stat is now "Unread load errors" (admin_stats.client_errors.unread), so the
red badge clears as you triage. Admin UI: Unread/Read/All tabs, a "Mark all read"
button, and a per-row ✓/↩ toggle; reading an entry drops it from the default view.
14-day auto-prune still bounds the table. Tests cover filter, toggle, mark-all,
404, and gating.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_admin.py

@@ -484,6 +484,37 @@ def test_client_error_telemetry(tmp_path, monkeypatch):
     assert stats["today"] == 1 and stats["window"] == 1  # bot excluded from both
 
 
+def test_client_error_read_unread(tmp_path, monkeypatch):
+    app, api = _make(tmp_path, monkeypatch, admin_email="boss@x.com")
+    anon = TestClient(app)
+    for r in ("boot-timeout", "preloadError", "boot-slow"):
+        anon.post("/api/client-error", json={"reason": r, "path": "/"})
+    tc = _signin(app, api, "boss@x.com")
+    # Default view is unread; all three start unread and drive the headline count.
+    unread = tc.get("/api/admin/client-errors").json()
+    assert len(unread) == 3 and all(not e["read"] for e in unread)
+    assert tc.get("/api/admin/stats").json()["client_errors"]["unread"] == 3
+    # Mark one read → it leaves the unread view, appears under read, count drops.
+    eid = unread[0]["id"]
+    assert tc.post(f"/api/admin/client-errors/{eid}/read", json={"read": True}).json()["read"] is True
+    assert len(tc.get("/api/admin/client-errors?show=unread").json()) == 2
+    rd = tc.get("/api/admin/client-errors?show=read").json()
+    assert len(rd) == 1 and rd[0]["id"] == eid and rd[0]["read"] is True
+    assert len(tc.get("/api/admin/client-errors?show=all").json()) == 3
+    assert tc.get("/api/admin/stats").json()["client_errors"]["unread"] == 2
+    # Toggling back restores it to unread.
+    assert tc.post(f"/api/admin/client-errors/{eid}/read", json={"read": False}).json()["read"] is False
+    assert len(tc.get("/api/admin/client-errors?show=unread").json()) == 3
+    # Mark-all clears the unread view in one go.
+    assert tc.post("/api/admin/client-errors/read-all").json()["marked"] == 3
+    assert tc.get("/api/admin/client-errors?show=unread").json() == []
+    assert tc.get("/api/admin/stats").json()["client_errors"]["unread"] == 0
+    # Unknown id 404s; both new routes are admin-gated.
+    assert tc.post("/api/admin/client-errors/99999/read", json={"read": True}).status_code == 404
+    assert anon.post("/api/admin/client-errors/read-all").status_code == 401
+    assert anon.post(f"/api/admin/client-errors/{eid}/read", json={"read": True}).status_code == 401
+
+
 def test_wordsearch_theme_admin(tmp_path, monkeypatch):
     app, api = _make(tmp_path, monkeypatch, admin_email="boss@x.com")
     assert TestClient(app).get("/api/admin/wordsearch/themes").status_code == 401  # gated