Migrate CSP middleware to Next.js proxy convention.

Renames src/middleware.ts to src/proxy.ts per Next.js 16 deprecation guidance. CSP nonce behavior is unchanged; build no longer emits the middleware warning.

Co-authored-by: Cursor <cursoragent@cursor.com>

desktop-shell/tauri-skeleton/README.md

@@ -75,7 +75,7 @@ The release build now does the full packaging pipeline:
 
 1. Generates branded icons in `src-tauri/icons/`
 2. Stages a desktop-only frontend export tree that omits Next server-only
-   routes/middleware (`src/app/api`, `src/middleware.ts`)
+   routes/proxy (`src/app/api`, `src/proxy.ts`)
 3. Stages a managed backend runtime bundle from `backend/` into
    `src-tauri/backend-runtime/`
 4. Builds the frontend export with `NEXT_OUTPUT=export`

desktop-shell/tauri-skeleton/RELEASE.md

@@ -52,7 +52,7 @@ See [RELEASE_INPUTS.md](./RELEASE_INPUTS.md) for the plain-language answer to
 
 1. Generates the desktop icon set in `src-tauri/icons/`
 2. Stages a desktop-only frontend export tree that omits Next server-only
-   routes/middleware (`src/app/api`, `src/middleware.ts`)
+   routes/proxy (`src/app/api`, `src/proxy.ts`)
 3. Stages a managed backend runtime bundle into `src-tauri/backend-runtime/`
 4. Builds the frontend export with `NEXT_OUTPUT=export`
 5. Copies `frontend/out` into `src-tauri/companion-www/`

desktop-shell/tauri-skeleton/scripts/build-frontend-export.cjs

@@ -17,7 +17,7 @@ const excludedPaths = [
   '.next',
   'out',
   'src/app/api',
-  'src/middleware.ts',
+  'src/proxy.ts',
 ];
 
 function normalizeRelativePath(target) {