feat(meetings): call log, past pagination + date filter; last-seen exact time (batch83)

#7 The past list was hard-capped at 12 (a .slice(0,12) in the client) and there was NO record
   of how many people were ever in a finished call — so the "only calls with >2 people" rule
   was impossible to apply. Added a call_history table: signaling tracks the HIGH-WATER
   participant count per room and logs the call when the room tears down (scheduled meetings
   are skipped — they already have their own row).
   Past meetings now follow the rules asked for:
     • a plain 1:1 direct call is NOT listed — unless it produced a recording/transcript
       (those already surface as recording entries);
     • a call that ever held MORE than 2 people IS listed (e.g. a 1:1 a third person joined),
       showing its participant count and duration;
     • entries are visible only to people who were actually in the call (or the group).
   Server-side pagination (10/page) + a from/to date filter; nothing is double-listed.

#2 Last seen now shows the exact time/date, WhatsApp-style — "last seen today at 1:36 PM",
   "last seen yesterday at 10:15 AM", "last seen 14/07/2026 at 9:00 AM" — instead of "10
   minutes ago".

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

server/db.js

@@ -238,6 +238,24 @@ try { db.exec('CREATE INDEX IF NOT EXISTS idx_users_bizgaze_user_id ON users(biz
 // When two accounts merge (#2), the merged-away row is deleted. This records old_id -> survivor so
 // any lingering reference to the old id (a cached contact, an in-flight DM) resolves to the survivor
 // instead of hitting a deleted user (which made messages to merged contacts silently vanish).
+// #7: a log of finished CALLS (ad-hoc / group / 1:1). Scheduled meetings already have their own row, so
+// they're not duplicated here. `peak` is the most people who were in the room at once — that's what lets
+// "Past meetings" show a call that grew past 2 people while hiding plain 1:1s.
+db.exec(`
+CREATE TABLE IF NOT EXISTS call_history (
+  id TEXT PRIMARY KEY,
+  team_id TEXT NOT NULL,
+  room TEXT NOT NULL,
+  group_id TEXT,
+  kind TEXT,
+  title TEXT,
+  peak INTEGER NOT NULL DEFAULT 0,
+  participants TEXT,
+  uids TEXT,
+  started_at INTEGER NOT NULL,
+  ended_at INTEGER NOT NULL
+)`);
+try { db.exec('CREATE INDEX IF NOT EXISTS idx_call_history_team ON call_history(team_id, ended_at)'); } catch (e) {}
 db.exec(`
 CREATE TABLE IF NOT EXISTS user_aliases (
   old_id TEXT PRIMARY KEY,