- 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`.
