Linux: browser helper for snap Firefox; packages register it

Snap Firefox starts the helper through the desktop portal, which reads the
manifest from ~/.mozilla or /usr/lib/mozilla. The .deb and .rpm now install the
manifests system-wide, and install.sh detects snap Firefox.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src-tauri/linux/app.kestrove.nmh.chrome.json

@@ -0,0 +1,7 @@
+{
+  "name": "app.kestrove.nmh",
+  "description": "Kestrove native messaging host",
+  "path": "/usr/bin/kestrove-nmh",
+  "type": "stdio",
+  "allowed_origins": ["chrome-extension://pmhfoafjoogobhfadaicklhkldgnafmk/", "chrome-extension://kogapfibnnpeapfcjkkpgjddbhnjfein/"]
+}

src-tauri/linux/app.kestrove.nmh.firefox.json

@@ -0,0 +1,7 @@
+{
+  "name": "app.kestrove.nmh",
+  "description": "Kestrove native messaging host",
+  "path": "/usr/bin/kestrove-nmh",
+  "type": "stdio",
+  "allowed_extensions": ["[email protected]"]
+}

src-tauri/tauri.conf.json

@@ -41,6 +41,24 @@
       "icons/icon.ico",
       "icons/icon.png"
     ],
+    "linux": {
+      "deb": {
+        "files": {
+          "/usr/lib/mozilla/native-messaging-hosts/app.kestrove.nmh.json": "linux/app.kestrove.nmh.firefox.json",
+          "/etc/opt/chrome/native-messaging-hosts/app.kestrove.nmh.json": "linux/app.kestrove.nmh.chrome.json",
+          "/etc/chromium/native-messaging-hosts/app.kestrove.nmh.json": "linux/app.kestrove.nmh.chrome.json",
+          "/etc/opt/edge/native-messaging-hosts/app.kestrove.nmh.json": "linux/app.kestrove.nmh.chrome.json"
+        }
+      },
+      "rpm": {
+        "files": {
+          "/usr/lib/mozilla/native-messaging-hosts/app.kestrove.nmh.json": "linux/app.kestrove.nmh.firefox.json",
+          "/etc/opt/chrome/native-messaging-hosts/app.kestrove.nmh.json": "linux/app.kestrove.nmh.chrome.json",
+          "/etc/chromium/native-messaging-hosts/app.kestrove.nmh.json": "linux/app.kestrove.nmh.chrome.json",
+          "/etc/opt/edge/native-messaging-hosts/app.kestrove.nmh.json": "linux/app.kestrove.nmh.chrome.json"
+        }
+      }
+    },
     "windows": {
       "nsis": {
         "installerHooks": "windows/hooks.nsh",