feat(06-01): scaffold apps/desktop as @tessera/desktop Tauri 2.x project

- Create Tauri project structure with Cargo.toml, tauri.conf.json, build.rs
- Implement lib.rs with store plugin and server URL navigation on startup
- Configure capabilities with core:default and store:default permissions
- Set frontendDist to ../src for local setup page (no bundled frontend)
- Add placeholder icons for build compatibility (to be replaced in 06-02)
- Add Cargo target/ to .gitignore
- Window config: 1280x800, centered, native decorations, resizable

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/desktop/src-tauri/tauri.conf.json

@@ -0,0 +1,32 @@
+{
+  "$schema": "https://raw.githubusercontent.com/tauri-apps/tauri/dev/crates/tauri-config-schema/schema.json",
+  "productName": "Tessera",
+  "version": "0.0.1",
+  "identifier": "de.ctl.tessera.desktop",
+  "build": {
+    "frontendDist": "../src",
+    "devUrl": "http://localhost:1420"
+  },
+  "app": {
+    "withGlobalTauri": true,
+    "windows": [
+      {
+        "label": "main",
+        "title": "Tessera",
+        "width": 1280,
+        "height": 800,
+        "center": true,
+        "decorations": true,
+        "resizable": true
+      }
+    ],
+    "security": {
+      "csp": "default-src 'self' 'unsafe-inline' 'unsafe-eval'; connect-src *; img-src * data:; font-src * data:; style-src 'self' 'unsafe-inline' *; script-src 'self' 'unsafe-inline' 'unsafe-eval' https://unpkg.com"
+    }
+  },
+  "bundle": {
+    "active": true,
+    "targets": ["appimage", "nsis"],
+    "icon": ["icons/icon.png", "icons/icon.ico"]
+  }
+}