chore: give the project its own identity instead of the scaffold's

Cargo.toml still carried `description = "A Tauri App"` and `authors = ["you"]`,
package.json's description was empty with no author or repository, and there was
no LICENSE file at all despite package.json declaring MIT.

The user-visible half matters more. productName was the scaffold's lowercase
"jellytau", which is what the Android *release* build shows under its icon and
what the deb/rpm/NSIS bundles carry as their display name. It went unnoticed
because build.gradle.kts overrides the label to "JellyTau Debug" for the debug
build type — the install a developer sees every day was the only correctly-cased
one. mainBinaryName pins the executable filename to "jellytau" so
build-windows-cross.sh and the Arch PKGBUILD, which both resolve it by name,
need no change.

strings.xml moves into the canonical android tree rather than being edited in
gen/, since sync-android-sources.sh already copies res/values/*.xml — so the fix
survives the next regeneration.

Bundle metadata (publisher, copyright, category, descriptions, licence) was
absent entirely, so the packages shipped with no maintainer or description. The
hand-written PKGBUILD and .desktop had all of it; only the generated packaging
was wrong.

Adds .env.example: three scripts require signing vars from a gitignored .env
and .gitignore already whitelists the example, but none existed.

TRACES: | DR-214

src-tauri/tauri.conf.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
-  "productName": "jellytau",
+  "productName": "JellyTau",
   "version": "0.8.2",
   "identifier": "com.dtourolle.jellytau",
   "build": {
@@ -25,19 +25,32 @@
       "devCsp": "default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval'; style-src 'self' 'unsafe-inline'; font-src 'self' data:; img-src 'self' data: blob: asset: http://asset.localhost http: https:; media-src 'self' blob: asset: http://asset.localhost http://127.0.0.1:* http: https:; connect-src 'self' ipc: http://ipc.localhost http: https: ws: wss:; worker-src 'self' blob:; object-src 'none'; frame-src 'none'; base-uri 'self'; form-action 'self'",
       "assetProtocol": {
         "enable": true,
-        "scope": ["$APPDATA/thumbnails/**"]
+        "scope": [
+          "$APPDATA/thumbnails/**"
+        ]
       }
     }
   },
   "bundle": {
     "active": true,
-    "targets": ["deb", "rpm", "nsis"],
+    "targets": [
+      "deb",
+      "rpm",
+      "nsis"
+    ],
     "icon": [
       "icons/32x32.png",
       "icons/128x128.png",
       "icons/128x128@2x.png",
       "icons/icon.icns",
       "icons/icon.ico"
-    ]
-  }
+    ],
+    "publisher": "Duncan Tourolle",
+    "copyright": "Copyright \u00a9 2026 Duncan Tourolle",
+    "category": "Video",
+    "shortDescription": "A cross-platform Jellyfin client",
+    "longDescription": "JellyTau is a Jellyfin client for Linux and Android. It streams and downloads music and video from a Jellyfin server, plays them back offline, and can control other Jellyfin sessions on the network.",
+    "licenseFile": "../LICENSE"
+  },
+  "mainBinaryName": "jellytau"
 }