feat(chat): emoji speed, action rework, copy, phone links, image zoom, upload %, profile card, last seen (batch82)

#6 Emoji were slow because Twemoji swapped EVERY emoji for an <img> fetched individually
   from a CDN — opening the picker fired hundreds of image requests. Now uses the OS's own
   colour emoji font: instant, zero network. twemojify() kept as a no-op.
#4 Message hover row reworked: three one-tap reactions (Like/Laugh/Surprised) + the emoji
   picker + (own) Edit. Reply / Forward / Copy / Delete moved behind a ⋮ menu. Added Copy.
   The row now sits FULLY above the bubble (was top:-14px, overlapping the first text line).
#9 Phone numbers linkify to tel: — mobile gets the OS "call this number?" prompt; desktop has
   no dialer so it offers to copy. Regex kept conservative (10–15 digits, needs +/grouping) so
   it won't grab amounts, dates or 6-digit meeting codes.
#3 Image preview zooms: wheel + pinch + double-click + ± buttons, drag to pan, keys (+/-/0),
   cursor-anchored. Arrows hide while zoomed so panning isn't hijacked.
#8 Upload progress: fetch() can't report upload progress at all, so a large file just said
   "uploading…". Switched to XHR (upload.onprogress) → real bar + %, and cancel aborts in flight.
#1 Clicking a sender in a group opens a mini profile card (photo, presence, last seen) with a
   Message button that opens the 1:1 (and a view-photo button).
#2 Last seen: new users.last_seen column, stamped on connect and when the last socket drops;
   carried on the presence broadcast, so an offline contact reads "Last seen 10 minutes ago"
   instead of a bare "Offline".

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

server/db.js

@@ -225,6 +225,9 @@ try { db.exec("ALTER TABLE users ADD COLUMN status TEXT NOT NULL DEFAULT 'active
 // their mobile number, so this — not the typed login identifier — is the stable identity key.
 // Provisioning matches on it to keep one Biz Connect account per person (#2 account merge).
 try { db.exec('ALTER TABLE users ADD COLUMN bizgaze_user_id TEXT'); } catch (e) { /* exists */ }
+// #2: when this user was last connected (stamped on connect + on their last socket closing), so contacts
+// can show "last seen 10 minutes ago" instead of a bare "Offline".
+try { db.exec('ALTER TABLE users ADD COLUMN last_seen INTEGER'); } catch (e) { /* exists */ }
 // External (non-Connect) invitee emails on a scheduled meeting (#4) — JSON array. They get an emailed
 // guest join link instead of an in-app invite.
 try { db.exec('ALTER TABLE scheduled_meetings ADD COLUMN guest_emails TEXT'); } catch (e) { /* exists */ }