Find libmosquitto and ship it in release packages (iteration 2, step 1)

cmake/Mosquitto.cmake finds it through pkg-config; with
FRAMEASSISTANT_SHIP_MOSQUITTO=ON (all package presets) it installs
lib/libmosquitto.so.1 and Debian's copyright file and excludes the
library from the Qt bundler (D35). The build containers get
libmosquitto-dev, the test container the mosquitto broker.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -242,6 +242,11 @@ hides world surfaces itself. Keep the teardown rule: overlays, then SteamVR, the
   the build tree and an install.
 - The manifest passes `--log-file logs/<exe>.log` (`arguments`), so SteamVR-started instances
   log to the install folder (or `build/<preset>/logs/` from the build tree).
+- **libmosquitto** (MQTT, D14/D35) comes from pkg-config (`cmake/Mosquitto.cmake`). The Frame
+  has none, so `FRAMEASSISTANT_SHIP_MOSQUITTO=ON` (all package presets) installs it into `lib/`
+  as `libmosquitto.so.1`, with Debian's copyright file (it contains the EPL-2.0/EDL-1.0
+  texts), and adds it to `VRDASH_BUNDLE_EXCLUDE`. Include it after `BundleQt`, which sets that
+  list.
 - `cmake/OpenVR.cmake` downloads only `openvr.h`, `LICENSE` and the matching
   `bin/linux64|linuxarm64/libopenvr_api.so` into `third_party/openvr-<ver>/` (gitignored).
 - **Deploying to the Frame uses its system Qt by default.** Bundling Qt is the fallback for