feat: multi-type file upload with sort order, labels, and expanded MIME support

- DB migration 007: add sort_order + display_label to thesis_files
- Database: getThesisFiles ordered by sort_order; insertThesisFile accepts label/order;
  new reorderThesisFiles() and updateThesisFileLabel() methods
- ThesisCreateController + ThesisEditController: expand allowed MIME/exts to include
  audio (mp3/ogg/wav/flac/aac/m4a), video (webm/mov/ogv), image (gif/webp),
  archives (tar/gz), any-ext via octet-stream; max size raised to 500 MB;
  accept file_labels[] and file_orders[] POST fields; detectFileType() helper
- MediaController: expanded MIME allowlist; HTTP Range support for audio/video;
  force-download for unknown types; inline for known displayable types
- fieldset-files.php: sortable queue UI with SortableJS, per-file labels, 500 MB hint
- templates/admin/edit.php: existing files as sortable list with drag handles,
  type icons, label inputs, delete checkboxes, hidden sort-order fields
- file-upload-queue.js: new JS replacing file-preview.js — sortable new-file queue,
  per-file labels, hidden order fields on submit, backward-compat legacy preview
- tfe.php: renders audio (<audio>), all video formats, images, PDF, and
  download-only 'other' files; reads display_label; sorted by sort_order
- tfe.css + form.css: styles for audio player, download files, sortable queue,
  drag handles, file type badges, label inputs
- .htaccess + .user.ini: upload_max_filesize=512M / post_max_size=520M

app/migrations/applied/007_thesis_files_sort_and_label.sql

@@ -0,0 +1,16 @@
+-- Migration 007: Add sort_order and display_label to thesis_files
+-- Also expand file type enum to cover audio and generic other types.
+
+ALTER TABLE thesis_files ADD COLUMN sort_order  INTEGER NOT NULL DEFAULT 0;
+ALTER TABLE thesis_files ADD COLUMN display_label TEXT;
+
+-- Back-fill sort_order from existing insertion order so ORDER BY sort_order
+-- is consistent with the old ORDER BY uploaded_at behaviour.
+UPDATE thesis_files SET sort_order = (
+    SELECT COUNT(*) FROM thesis_files tf2
+    WHERE tf2.thesis_id = thesis_files.thesis_id
+      AND (tf2.sort_order < thesis_files.sort_order
+           OR (tf2.sort_order = 0 AND tf2.uploaded_at < thesis_files.uploaded_at)
+           OR (tf2.sort_order = 0 AND tf2.uploaded_at = thesis_files.uploaded_at AND tf2.id < thesis_files.id))
+) + 1
+WHERE sort_order = 0;