fix(collections): browser-verification pass over the unified builder/editor

The real-browser sweep (the gotcha classes' native habitat — CSP refusals
fail SILENTLY at build/test time) found four defects, all in the item
3.3/3.4 surfaces:

- Shared builder rows used Alpine attribute expressions that the CSP
  parser rejects outright: backtick template literals in :style, the
  ?. optional chain in :placeholder/x-if, and an if-STATEMENT in a
  @click.outside. Rewritten as string concat plus two component methods
  (fieldIsDays, dismissSuggestions). Until this fix every drawer open
  threw a wall of "CSP Parser Error" console noise and the days-value
  affordance never rendered.
- "2 bookss match": the count noun is interpolated into "<n> <noun>s
  match", so callers must pass the SINGULAR ("book"/"item").
- The rules editor page received its fields/tree payloads from the
  route as already-JSON-encoded strings and wrapped them in JSONArg
  AGAIN — double-encoded, so JSON.parse yields a string and the editor
  loaded with NO vocabulary and NO prefill. The route now emits raw
  JSON into the data attributes (single encode).
- Apply was silently inert: the hook store round-trip used
  window.Alpine?.store (optional-chained, no-op when absent) and the
  Cancel/Apply block sat outside the builder island scope for part of
  the session. Both fixed via the imported Alpine instance and moving
  the buttons inside the island; Apply now PUTs the tree end-to-end
  (verified live: prefill → edit → apply → 201 → reload → membership).

Browser-verified clean (no fixes needed): picker scope tabs + episode
grid (?scope=episodes door), selection store across swaps, Add Selected
episode membership, library-switcher partial contract (episodes visible
under All Libraries, correctly filtered out under a book library — and
now never OFFERED as a switcher option), episode cards + reorder arrows
persisting position, collection-chain player (Ep N/M, prev/next carry
?queue=collection:, order control absent in collection mode and present
+ persistent in feed mode both in player and feed page), and the
empty-tree Apply guard (400 — a static collection can never be
promoted by accident).

Notes for the next reader of these lines: the OpenChamber panel's
browser.select sets select.value without dispatching change, so htmx
change-triggers must be exercised by real events (Playwright) rather
than the panel; and one 500 was observed on the player's leave-page
progress PUT — a request whose context the navigating browser cancels
mid-write, pre-existing and benign (the immediately following save
returned 200).

templates/bookshelf_templ.go

@@ -424,7 +424,7 @@ func BookShelf(
 		if templ_7745c5c3_Err != nil {
 			return templ_7745c5c3_Err
 		}
-		templ_7745c5c3_Err = FilterBuilderRows("books").Render(ctx, templ_7745c5c3_Buffer)
+		templ_7745c5c3_Err = FilterBuilderRows("book").Render(ctx, templ_7745c5c3_Buffer)
 		if templ_7745c5c3_Err != nil {
 			return templ_7745c5c3_Err
 		}