refactor(documents): split the vault page into filters, library, selection and detail

DocumentsView carried 970 lines of state before its first element. The
state moves to components/documents/vault/:

- selection-history: the `?doc=` history entry helpers (pure, tested)
- use-vault-filters: URL filters, the debounced search and the `/` key
- use-vault-library: usage, the paged list and its processing poll,
  layout, uploads and their intake paths, the corpus-index affordance
- use-vault-filter-choices: conditions, procedures, visits, years
- use-vault-selection and use-vault-bulk: the selection with ranges and
  Escape, the confirmed delete, re-filing, linking and the bulk share
- use-vault-detail: the detail sheet driven by `?doc=`, its close and
  the check that the close took
- vault-page-actions, vault-drop-overlay

The page composes them in about 300 lines; markup and behaviour are
unchanged, and the guards follow the code they watch.

src/__tests__/baselines/source-function-lines.json

@@ -1,7 +1,7 @@
 {
   "$comment": "Production functions over 200 lines, keyed \"file :: name\", and their length. Maintained by src/__tests__/source-size-ratchet.test.ts.",
   "count": 405,
-  "total": 140971,
+  "total": 140305,
   "entries": {
     "app/achievements/page.tsx :: AchievementsPage": 206,
     "app/api/admin/backups/upload/route.ts :: apiHandler(arg)": 314,
@@ -127,7 +127,7 @@
     "components/documents/document-filter-bar.tsx :: DocumentFilterBar": 348,
     "components/documents/document-record-links.tsx :: DocumentRecordLinks": 202,
     "components/documents/document-timeline.tsx :: DocumentTimeline": 314,
-    "components/documents/documents-view.tsx :: DocumentsView": 969,
+    "components/documents/documents-view.tsx :: DocumentsView": 303,
     "components/documents/sources/document-source-picker.tsx :: DocumentSourcePicker": 565,
     "components/illness/log-day-sheet.tsx :: LogDaySheet": 265,
     "components/illness/new-episode-sheet.tsx :: NewEpisodeSheet": 264,