fix: use getElementById for relink FilePond pool lookup

FilePond 4.x wraps the original input element in its own DOM structure
which can break CSS attribute selectors. querySelector with
.tfe-file-picker[data-queue-type='...'] returned null even though the
element existed and was initialized.

Switched to getElementById with a queueType→inputId map:
  cover → couverture
  note_intention → note_intention
  tfe → tfe-files-input
  annexe → annexe-files-input

getElementById is both faster and immune to FilePond's DOM wrapping.

TODO.md

@@ -1,17 +1,3 @@
 # TODO
 
-- [x] Fix CSP: add `frame-src` to allow iframes from `videos.erg.be` and `depnum.happyngreen.fr`
-- [x] Website iframe overlay: remove blur, move button to bottom-right, replace text with SVG icon + tooltip
-- [x] Fix "Copier" button in logs section scrolling out of view on horizontal scroll
-- [x] Remove TOC temporary debug error_log calls
-- [x] Fix PeerTube upload failure: PHP /tmp tmpfs too small for large video files
-- [x] Fix keyword word-breaking in repertoire.php: widen kw grid column, add white-space: nowrap
-- [x] Fix licence.php TOC: restore `open` attribute on `<details class="toc">` (lost in vrxsstns, never restored by uuomvtvm fix)
-- [x] Fix hasFilePondQueueData() missing peertube: prefix check → new PeerTube uploads silently lost on edit
-- [x] Fix handleWebsiteUrl() in ThesisEditController unconditionally deleting website rows on every edit
-- [x] Fix FilePond server.remove potentially triggering during HTMX fragment teardown
-- [x] Add restore-from-corbeille functionality in cleanup page
-- [x] Fix cleanup stats: use sidecar JSON for restorability classification (not DB row existence)
-- [x] Remove destructive HTMX fragment refresh from relink flow (close modal only, pond.addFile in-place)
-- [x] Merge corbeille lists into single table with status column + bulk restore button
-- [x] Fix relinked file not appearing in FilePond UI: use addFiles([{type:'local'}]) instead of addFile(type:'limbo')
+- [x] Fix relinked file not appearing in FilePond UI: switch to ID-based input lookup