Replace Psalm with PHPStan + PHP‑CS‑Fixer + Biome, add linting configs & cleanup

- Removed the `vimeo/psalm` dependency and all related files
(`psalm.xml`, `psalm‑baseline.xml`, suppress annotations).  
- Added **PHPStan** (v2.1.54) and **PHP‑CS‑Fixer** (v3.95.1) to
`vendor/bin/`.  
- Created `phpstan.neon` (level 5, bootstraps `app/bootstrap.php`,
scans `Parsedown.php`).  
- Created `phpstan‑baseline.neon` with 10 pre‑existing errors.  
- Added `.php‑cs‑fixer.dist.php` (PSR‑12 + PHP80Migration, targets
 `app/src` & `app/tests`).  
- Added `biome.json` and updated `justfile` to replace the old Psalm
recipes with `phpstan`, `cs‑check`, and `cs‑fix`.  
- Updated `.gitignore` to exclude PHPStan and PHP‑CS‑Fixer cache files.  
- Updated several JS files (`file‑preview.js`, `file‑upload‑queue.js`)
eand PHP controllers (`MediaController.php`, `SearchController.php`,
`SystemController.php`).  
- Minor adjustments to `TODO.md`, `app/src/Database.php`,
`app/src/Parsedown.php`, `app/src/ShareLink.php`, and
`app/src/SmtpRelay.php`.

app/src/Controllers/MediaController.php

@@ -109,14 +109,9 @@ class MediaController
         // 5. Determine if download was explicitly requested
         $forceDownload = !empty($_GET['download']) && $_GET['download'] === '1';
 
-        // File types that should be displayed inline by default
-        $inlineExts = ['jpg','jpeg','png','gif','webp','pdf','mp4','webm','ogv','mov',
-                       'mp3','ogg','oga','wav','flac','aac','m4a','vtt'];
-        $inline = in_array($ext, $inlineExts, true) && !$forceDownload;
-
         // 6. Send response headers
         header('Content-Type: ' . $mimeType);
-        header('Content-Length: ' . filesize($realFull));
+        header('Content-Length: ' . (int) filesize($realFull));
         header('X-Content-Type-Options: nosniff');
 
         if ($ext === 'vtt') {
@@ -155,7 +150,7 @@ class MediaController
      */
     private function streamWithRange(string $path, string $mimeType): void
     {
-        $size  = filesize($path);
+        $size  = (int) filesize($path);
         $start = 0;
         $end   = $size - 1;