feat(v2): add packaging, installer, and CI release workflow (Phase 6)

Build-from-source installer (install-v2.sh) with dependency checks for
Node.js 20+, Rust 1.77+, and system libraries. Tauri bundle config for
.deb and AppImage targets. GitHub Actions workflow builds and uploads
release artifacts on version tags. Icons regenerated as RGBA PNGs.

v2/src-tauri/tauri.conf.json

@@ -26,13 +26,30 @@
   },
   "bundle": {
     "active": true,
-    "targets": "all",
+    "targets": ["deb", "appimage"],
     "icon": [
       "icons/32x32.png",
       "icons/128x128.png",
       "icons/128x128@2x.png",
       "icons/icon.icns",
       "icons/icon.ico"
-    ]
+    ],
+    "category": "DeveloperTool",
+    "shortDescription": "Multi-session Claude agent dashboard",
+    "longDescription": "BTerminal is a terminal emulator with integrated Claude AI agent sessions, SSH management, and a tiling pane layout. Built with Tauri, Svelte 5, and xterm.js.",
+    "linux": {
+      "deb": {
+        "depends": [
+          "libwebkit2gtk-4.1-0",
+          "libgtk-3-0",
+          "libayatana-appindicator3-1"
+        ],
+        "section": "devel",
+        "priority": "optional"
+      },
+      "appimage": {
+        "bundleMediaFramework": false
+      }
+    }
   }
 }