feat(kanban): reporte diario al click en dia del calendario (issue 0093)

Adds a daily report dashboard accessible by clicking a day number in the
calendar view. Renders inside a full-width modal (90% width).

Backend (new file backend/reports.go):
- Type DailyReport with KPIs, rankings, done_cards list, reopened cards,
  3-bucket stale list (7/14/30d), lead time avg+p50+p95, 24-hour
  movement histogram, deadlines met/missed list, tag distribution and
  archived count.
- DB.DailyReportFor(date, tz) uses Europe/Madrid by default; computes
  [start,end) in local time, converts to UTC and queries:
  * cards.completed_at in range  -> done list
  * card_events kind=created in range -> created counts
  * card_column_history.entered_at in range -> moves + hourly
  * previousColumnWasDone() -> reopened detection
  * card_lock_history overlapping the day -> blocked_ms
  * stale buckets: open history entries on non-done columns aged >=7d
- New route GET /api/reports/daily?date=YYYY-MM-DD&tz=Europe/Madrid.

Frontend:
- api.ts: DailyReport type + dailyReport(date, tz?) call.
- New component DailyReportView (components/DailyReport.tsx):
  * 6 KPI cards (Hechas, Creadas, Movimientos, Bloqueado, Reabiertas,
    Deadlines on-time %).
  * 4 ranking cards (Top assignees done, Top assignees created,
    Top requesters atendidas, Top requesters aportadas).
  * Done cards table with click-to-jump (links open the card in board).
  * Mantine BarChart with movements per hour.
  * Tag chips, reopened list, deadlines list with late_ms, stale buckets.
- CalendarView wraps the day number in UnstyledButton with data-test
  attribute and forwards onOpenDailyReport.
- App.handleOpenDailyReport opens modals.open size 90% with the view;
  click on a card title closes the modal and jumps to the board with
  highlight (reuses existing handleJumpToCard).

Tests (e2e/daily-report.spec.ts):
- Endpoint shape: kpis, done_cards, hourly_moves[24], stale buckets.
- Calendar day click opens the modal with "Reporte diario" title and
  KPI labels visible.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/api.ts

@@ -119,6 +119,90 @@ export function unarchiveCard(id: string): Promise<void> {
   return fetchJSON(`/cards/${id}/unarchive`, { method: "POST" });
 }
 
+export interface DailyReport {
+  date: string;
+  tz: string;
+  start_ts: string;
+  end_ts: string;
+  kpis: {
+    done: number;
+    created: number;
+    moves: number;
+    blocked_ms: number;
+    deadlines_met: number;
+    deadlines_missed: number;
+    reopened: number;
+    archived_auto: number;
+    archived_manual: number;
+  };
+  top_assignees_done: { user_id: string; name: string; count: number }[];
+  top_assignees_created: { user_id: string; name: string; count: number }[];
+  top_requesters_added: { name: string; count: number }[];
+  top_requesters_done: { name: string; count: number }[];
+  done_cards: {
+    id: string;
+    seq_num: number;
+    title: string;
+    requester: string;
+    assignee_id: string | null;
+    assignee_name: string | null;
+    tags: string[];
+    column_id: string;
+    column_name: string;
+    completed_at: string;
+    created_at: string;
+    lead_time_ms: number;
+    color: string;
+  }[];
+  reopened_cards: {
+    card_id: string;
+    title: string;
+    seq_num: number;
+    from_column: string;
+    to_column: string;
+    ts: string;
+    actor_id: string | null;
+    actor_name: string | null;
+  }[];
+  stale_cards: {
+    d7: StaleEntry[];
+    d14: StaleEntry[];
+    d30: StaleEntry[];
+  };
+  lead_time: { avg_ms: number; p50_ms: number; p95_ms: number; samples: number };
+  hourly_moves: number[];
+  deadlines: {
+    met: number;
+    missed: number;
+    list: {
+      card_id: string;
+      title: string;
+      seq_num: number;
+      deadline: string;
+      completed_at: string;
+      late_ms: number;
+    }[];
+  };
+  tags_done: { name: string; count: number }[];
+  archived_today: number;
+}
+
+export interface StaleEntry {
+  card_id: string;
+  title: string;
+  seq_num: number;
+  column_id: string;
+  column_name: string;
+  entered_at: string;
+  days: number;
+}
+
+export function dailyReport(date: string, tz?: string): Promise<DailyReport> {
+  const params = new URLSearchParams({ date });
+  if (tz) params.set("tz", tz);
+  return fetchJSON(`/reports/daily?${params.toString()}`);
+}
+
 export function moveCard(id: string, column_id: string, ordered_ids: string[]): Promise<void> {
   return fetchJSON(`/cards/${id}/move`, {
     method: "POST",