Release 0.6.2 + AppImage packaging

Bump to 0.6.2 (Cargo + Inno .iss), promote CHANGELOG [Unreleased] -> [0.6.2].
0.6.2 rolls up the licensing (MIT + THIRD_PARTY_LICENSES) and the friends-list
liveness fixes (active offline marking, 15s refresh, manual Rescan) on the
0.6.x wire format (gossip v5, compatible with 0.6.0/0.6.1).

Adds packaging/appimage: a thin AppImage recipe (linuxdeploy) that bundles the
pixelpass screen-share helper in usr/bin so peerspeak's $PATH lookup finds it
with no code change. Assets are include_bytes!-embedded; the graphics stack and
pixelpass's gstreamer/mpv tools are left to the host. Built on Ubuntu 24.04
(glibc 2.39) for reach across Debian 13+/Fedora 40+/rolling.

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

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 All notable changes to PeerSpeak are documented here.
 
-## [Unreleased]
+## [0.6.2] — 2026-07-03
 
 ### Fixed
 - **Friends list now reflects status changes without a restart.** A presence probe that fails now actively marks the friend **offline**, so a friend who goes offline, leaves a room, or turns invisible no longer lingers showing a stale "online" / "in a room" status until PeerSpeak is relaunched. Previously only successful probes updated the list, so it could ratchet a friend's status up but never down. The auto-refresh interval was also shortened from 60s to **15s** so the list tracks changes more closely.
@@ -13,6 +13,8 @@ All notable changes to PeerSpeak are documented here.
 ### Licensing
 - **PeerSpeak is now released under the MIT License** (previously an unlicensed private build). Added a `LICENSE` file and a `THIRD_PARTY_LICENSES` file enumerating the full dependency manifest plus the canonical text of every referenced license, with notices for the statically bundled Opus codec and the embedded fonts (Iced-Icons, Cantarell/OFL-1.1). Both files ship in the Arch and Debian packages.
 
+[0.6.2]: https://gitbutter.xyz/mollusk/peerspeak/releases/tag/v0.6.2
+
 ## [0.6.0] — 2026-06-28
 
 ### Added