feat(edit): thumbnail + video file upload in Edit modal (steps 2-3/3)

Brings the Edit modal to upload parity with the Upload modal: re-upload a
thumbnail or video file instead of only pasting URLs.

- Wire storage services (r2/s3/storageService) + pubkey/npub accessors into
  EditModal via ModalManager/initEditModal; EditModal constructs a shared
  MediaUploader.
- New editModalUpload.js holds all the upload glue (file-picker wiring, progress,
  storage-unlock checks, field write-back) to keep EditModal under its file-size
  budget. EditModal calls initEditModalUpload(this, context) in one line.
- edit-video-modal.html: "Replace video file…" (under the URL field) and
  "Replace thumbnail file…" (under the thumbnail field), each with a hidden file
  input + status line.
- On thumbnail upload: writes the new URL into the thumbnail field. On video
  upload: writes url + magnet (+ ws/xs hints). All written via setFieldUnlocked,
  which marks the field edited so EditModal.collect actually persists it (gated
  behind storage being configured + unlocked).

setFieldUnlocked is unit-tested (mutation-verified): without the unlock, the
re-upload would silently not save. Build + full lint + unit suite green.

NOTE: the upload/storage flow itself can't be unit-tested (browser + R2/S3);
pending manual verification of editing a video's thumbnail/file.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

js/ui/initEditModal.js

@@ -14,6 +14,9 @@ export function initEditModal({
   const {
     getMode = null,
     sanitizers = {},
+    r2Service = null,
+    s3Service = null,
+    storageService = null,
   } = services;
 
   const {
@@ -24,6 +27,9 @@ export function initEditModal({
 
   const {
     showError = null,
+    showSuccess = null,
+    getCurrentPubkey = null,
+    safeEncodeNpub = null,
     onSubmit = null,
     onCancel = null,
   } = callbacks;
@@ -36,9 +42,15 @@ export function initEditModal({
       removeTrackingScripts: removeTrackingScriptsFn,
       setGlobalModalState: setGlobalModalStateFn,
       showError,
+      showSuccess,
       getMode,
       sanitizers,
       escapeHtml,
+      r2Service,
+      s3Service,
+      storageService,
+      getCurrentPubkey,
+      safeEncodeNpub,
       eventTarget: events,
       container,
     });