Round 2 fixes from on-device testing (#2,#3,#6,#8,#9,#13,#14,#18 + call re-ring)

#2  Don't ping/notify when you're ACTIVELY viewing a chat (app visible + chat
    open). Alert only when a different chat, OR the open chat while the app is
    minimised (the backgrounded case that used to stay silent).
#3  A reaction to my message now raises an unread badge on that conversation
    (like a new message), not just a notification.
#6  Image lightbox pulls EVERY image in the conversation via /api/messages/media
    (older images aren't in the DOM yet) — nav arrows reach them all. Nav buttons
    always in the DOM; syncArrows shows/hides at the ends and for a single image.
#8  On app resume (visibilitychange / native appStateChange), reconnect the chat
    socket if it isn't OPEN and re-pull the sidebar so online/last-seen refresh —
    iOS freezes the WebView so the socket can be dead while its onclose lags,
    leaving contacts stuck on a stale "Offline".
#9  Real cause was iOS "sticky :hover": a single tap latched :hover and popped the
    action bar. Gate the hover-reveal behind @media (hover:hover) so touch reveals
    actions ONLY via long-press; a plain tap performs the primary action.
#13 Pinned bar gains a "‹ 1 of n ›" pager to walk through multiple pinned messages
    (shown only when more than one is pinned).
#14 Editing a message no longer eats a half-written draft — the real draft is set
    aside on edit start and restored on save/cancel. edited_at is now in the message
    DTO so the "edited" tag survives a reload.
#18 One "Delete" entry opens a branded dialog with "Delete for me" / "Delete for
    everyone" (icons + descriptions) and a ✕/backdrop cancel, replacing the two
    separate menu items.
New: a participant who LEAVES a still-running call is no longer auto-rung back in
    on every socket reconnect. Track who left per call; replayActiveCalls sends
    them noRing state (refreshes the Join affordance without ringing). An explicit
    re-invite clears that and rings again.

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

server/public/icons.js

@@ -24,6 +24,7 @@
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     trash:       '<path d="M3 6h18"/><path d="M19 6v14a2 2 0 0 1-2 2H7a2 2 0 0 1-2-2V6m3 0V4a2 2 0 0 1 2-2h4a2 2 0 0 1 2 2v2"/>',
+    eyeOff:      '<path d="M9.88 9.88a3 3 0 1 0 4.24 4.24"/><path d="M10.73 5.08A10.43 10.43 0 0 1 12 5c7 0 10 7 10 7a13.16 13.16 0 0 1-1.67 2.68"/><path d="M6.61 6.61A13.526 13.526 0 0 0 2 12s3 7 10 7a9.74 9.74 0 0 0 5.39-1.61"/><path d="m2 2 20 20"/>',
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