feat: rebrand AgendaPro -> AgendaMax + calendar fixes + current-week demo seed

- Rebrand all user-facing text to AgendaMax
- Fix sidebar scrolling: card container no longer overflows html (flex h-full min-h-0)
- Fix calendar toolbar hover: active buttons keep readable contrast
- Sticky calendar toolbar (month/week/day always visible on scroll)
- Seed guarantees 2-4 appointments per day for current week (Mon-Sat)

server/lib/time.ts

@@ -0,0 +1,117 @@
+// server/lib/time.ts
+// Pure timezone helpers for business-local ("biz") date math.
+// Mexico is UTC-6, so SQLite date('now') (= UTC) misattributes the evening rush.
+// All functions are deterministic given an explicit instant (default = new Date()).
+
+/** Returns the calendar date (YYYY-MM-DD) of the given instant in the given IANA tz. */
+export function bizDateISO(instant: Date, tz: string): string {
+  return new Intl.DateTimeFormat("en-CA", {
+    timeZone: tz || "UTC",
+    year: "numeric",
+    month: "2-digit",
+    day: "2-digit",
+  }).format(instant); // en-CA yields "YYYY-MM-DD"
+}
+
+/** Business "today" (YYYY-MM-DD) for a tz, at the given instant (default: server now). */
+export function bizTodayISO(tz: string, now: Date = new Date()): string {
+  return bizDateISO(now, tz);
+}
+
+/** tz offset (in minutes) of the given instant, east of UTC positive. */
+function tzOffsetMinutes(instant: Date, tz: string): number {
+  const parts = new Intl.DateTimeFormat("en-US", {
+    timeZone: tz || "UTC",
+    timeZoneName: "longOffset",
+  }).formatToParts(instant);
+  const off = parts.find((p) => p.type === "timeZoneName")?.value ?? "GMT+00:00";
+  // e.g. "GMT-06:00", "GMT+05:30", "GMT+00:00", or bare "GMT" for UTC
+  const m = off.match(/GMT([+-])(\d{1,2})(?::(\d{2}))?/);
+  if (!m) return 0; // bare "GMT" → UTC
+  const sign = m[1] === "-" ? -1 : 1;
+  const h = parseInt(m[2], 10);
+  const min = m[3] ? parseInt(m[3], 10) : 0;
+  return sign * (h * 60 + min);
+}
+
+/**
+ * Convert a business-local wall-clock (year, month, day, hh, mm, ss) in `tz` to a UTC Date.
+ * We first treat the wall-clock as if it were UTC, read the tz offset at that instant,
+ * then subtract the offset: a west tz (negative offset) is "behind" UTC, so the same
+ * wall-clock happens later in UTC → UTC = wall − offset.
+ */
+export function wallToUtcDate(
+  tz: string,
+  y: number,
+  mo: number,
+  d: number,
+  hh: number,
+  mm: number,
+  ss: number
+): Date {
+  const guess = new Date(Date.UTC(y, mo - 1, d, hh, mm, ss));
+  const offsetMin = tzOffsetMinutes(guess, tz);
+  return new Date(guess.getTime() - offsetMin * 60000);
+}
+
+/** Business-day UTC bounds (start = local 00:00:00, end = local 23:59:59) for today +/- offset. */
+export function bizDayBounds(
+  tz: string,
+  dayOffset = 0,
+  now: Date = new Date()
+): { start: Date; end: Date } {
+  const today = bizDateISO(now, tz);
+  const [y, m, d] = today.split("-").map(Number);
+  const base = new Date(Date.UTC(y, m - 1, d));
+  base.setUTCDate(base.getUTCDate() + dayOffset);
+  const ty = base.getUTCFullYear();
+  const tm = base.getUTCMonth() + 1;
+  const td = base.getUTCDate();
+  return {
+    start: wallToUtcDate(tz, ty, tm, td, 0, 0, 0),
+    end: wallToUtcDate(tz, ty, tm, td, 23, 59, 59),
+  };
+}
+
+/** Format a UTC instant as SQLite canonical "YYYY-MM-DD HH:MM:SS" (matches datetime() output). */
+export function toSqliteUtc(d: Date): string {
+  return d.toISOString().slice(0, 19).replace("T", " ");
+}
+
+/** Format a UTC instant as ISO "YYYY-MM-DDTHH:MM:SSZ" (matches the stored start_at format). */
+export function toIsoUtc(d: Date): string {
+  return d.toISOString().slice(0, 19) + "Z";
+}
+
+/** Business-day bounds in SQLite canonical format — pair with `datetime(column) >= ?`. */
+export function bizDayBoundsSqlite(
+  tz: string,
+  dayOffset = 0,
+  now: Date = new Date()
+): { start: string; end: string } {
+  const b = bizDayBounds(tz, dayOffset, now);
+  return { start: toSqliteUtc(b.start), end: toSqliteUtc(b.end) };
+}
+
+/** Business-day bounds in ISO-Z format — pair with raw `start_at >= ?`. */
+export function bizDayBoundsIso(
+  tz: string,
+  dayOffset = 0,
+  now: Date = new Date()
+): { start: string; end: string } {
+  const b = bizDayBounds(tz, dayOffset, now);
+  return { start: toIsoUtc(b.start), end: toIsoUtc(b.end) };
+}
+
+/** Convenience: convert a business-local wall-clock to a UTC ISO string. */
+export function wallToUtcISO(
+  tz: string,
+  y: number,
+  mo: number,
+  d: number,
+  hh: number,
+  mm: number,
+  ss: number
+): string {
+  return wallToUtcDate(tz, y, mo, d, hh, mm, ss).toISOString();
+}