feat(registratura): add legal deadline tracking system (Termene Legale)

Full deadline tracking engine for Romanian construction permitting:
- 16 deadline types across 5 categories (Avize, Completări, Analiză, Autorizare, Publicitate)
- Working days vs calendar days with Romanian public holidays (Orthodox Easter via Meeus)
- Backward deadlines (AC extension: 45 working days BEFORE expiry)
- Chain deadlines (resolving one prompts adding the next)
- Tacit approval auto-detection (overdue + applicable type)
- Tabbed UI: Registru + Termene legale dashboard with stats/filters/table
- Inline deadline cards in entry form with add/resolve/remove
- Clock icon + count badge on registry table for entries with deadlines

Also adds CLAUDE.md with full project context for AI assistant handoff.

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

src/modules/registratura/services/working-days.ts

@@ -0,0 +1,146 @@
+/**
+ * Romanian working-day arithmetic.
+ *
+ * Fixed public holidays + Orthodox Easter-derived moveable feasts.
+ * Uses the Meeus algorithm for Orthodox Easter computation.
+ */
+
+// ── Fixed Romanian public holidays (month is 0-indexed) ──
+
+interface FixedHoliday {
+  month: number;
+  day: number;
+}
+
+const FIXED_HOLIDAYS: FixedHoliday[] = [
+  { month: 0, day: 1 },   // Anul Nou
+  { month: 0, day: 2 },   // Anul Nou (zi 2)
+  { month: 0, day: 24 },  // Ziua Unirii
+  { month: 4, day: 1 },   // Ziua Muncii
+  { month: 5, day: 1 },   // Ziua Copilului
+  { month: 7, day: 15 },  // Adormirea Maicii Domnului
+  { month: 10, day: 30 }, // Sfântul Andrei
+  { month: 11, day: 1 },  // Ziua Națională
+  { month: 11, day: 25 }, // Crăciunul
+  { month: 11, day: 26 }, // Crăciunul (zi 2)
+];
+
+// ── Orthodox Easter via Meeus algorithm ──
+
+function orthodoxEaster(year: number): Date {
+  const a = year % 4;
+  const b = year % 7;
+  const c = year % 19;
+  const d = (19 * c + 15) % 30;
+  const e = (2 * a + 4 * b - d + 34) % 7;
+  const month = Math.floor((d + e + 114) / 31); // 3 = March, 4 = April
+  const day = ((d + e + 114) % 31) + 1;
+
+  // Julian date — convert to Gregorian by adding 13 days (valid 1900–2099)
+  const julian = new Date(year, month - 1, day);
+  julian.setDate(julian.getDate() + 13);
+  return julian;
+}
+
+function getMovableHolidays(year: number): Date[] {
+  const easter = orthodoxEaster(year);
+
+  const goodFriday = new Date(easter);
+  goodFriday.setDate(easter.getDate() - 2);
+
+  const easterMonday = new Date(easter);
+  easterMonday.setDate(easter.getDate() + 1);
+
+  const rusaliiSunday = new Date(easter);
+  rusaliiSunday.setDate(easter.getDate() + 49);
+
+  const rusaliiMonday = new Date(easter);
+  rusaliiMonday.setDate(easter.getDate() + 50);
+
+  return [goodFriday, easter, easterMonday, rusaliiSunday, rusaliiMonday];
+}
+
+// ── Holiday cache per year ──
+
+const holidayCache = new Map<number, Set<string>>();
+
+function toKey(d: Date): string {
+  return `${d.getFullYear()}-${String(d.getMonth() + 1).padStart(2, '0')}-${String(d.getDate()).padStart(2, '0')}`;
+}
+
+function getHolidaySet(year: number): Set<string> {
+  const cached = holidayCache.get(year);
+  if (cached) return cached;
+
+  const set = new Set<string>();
+
+  for (const h of FIXED_HOLIDAYS) {
+    set.add(toKey(new Date(year, h.month, h.day)));
+  }
+
+  for (const d of getMovableHolidays(year)) {
+    set.add(toKey(d));
+  }
+
+  holidayCache.set(year, set);
+  return set;
+}
+
+// ── Public API ──
+
+export function isPublicHoliday(date: Date): boolean {
+  return getHolidaySet(date.getFullYear()).has(toKey(date));
+}
+
+export function isWeekend(date: Date): boolean {
+  const day = date.getDay();
+  return day === 0 || day === 6;
+}
+
+export function isWorkingDay(date: Date): boolean {
+  return !isWeekend(date) && !isPublicHoliday(date);
+}
+
+/**
+ * Add calendar days (simply skips no days).
+ * Supports negative values.
+ */
+export function addCalendarDays(start: Date, days: number): Date {
+  const result = new Date(start);
+  result.setDate(result.getDate() + days);
+  return result;
+}
+
+/**
+ * Add working days, skipping weekends and Romanian public holidays.
+ * Supports negative values (for backward deadlines).
+ */
+export function addWorkingDays(start: Date, days: number): Date {
+  const result = new Date(start);
+  const direction = days >= 0 ? 1 : -1;
+  let remaining = Math.abs(days);
+
+  while (remaining > 0) {
+    result.setDate(result.getDate() + direction);
+    if (isWorkingDay(result)) {
+      remaining--;
+    }
+  }
+
+  return result;
+}
+
+/**
+ * Compute the due date for a deadline definition.
+ */
+export function computeDueDate(
+  startDate: Date,
+  days: number,
+  dayType: 'calendar' | 'working',
+  isBackward?: boolean,
+): Date {
+  const effectiveDays = isBackward ? -days : days;
+  return dayType === 'working'
+    ? addWorkingDays(startDate, effectiveDays)
+    : addCalendarDays(startDate, effectiveDays);
+}