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/collection_rules.templ

@@ -21,7 +21,7 @@ templ CollectionRules(user User, collection CollectionData, fieldsJSON string, t
 			class={ "theme-" + user.Theme }
 			x-data="collectionRules"
 			data-collection-name={ collection.Name }
-			x-init={ "initCollectionRules('" + collection.ID + "', '" + scope + "', " + JSONArg(treeJSON) + ")" }
+			x-init={ "initCollectionRules('" + collection.ID + "', '" + scope + "')" }
 		>
 			@Header(user, "/collections")
 			<div class="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 py-8">
@@ -52,15 +52,15 @@ templ CollectionRules(user User, collection CollectionData, fieldsJSON string, t
 				     root mode IS the collection's match semantics. -->
 				<div
 					x-data="filterBuilderExtra"
-					data-filter-fields={ JSONArg(fieldsJSON) }
-						data-scope={ scope }
-					data-tree={ JSONArg(treeJSON) }
+					data-filter-fields={ fieldsJSON }
+					data-scope={ scope }
+					data-tree={ treeJSON }
 					class="card p-6"
 				>
 					<div class="flex items-center justify-between mb-3 px-1">
 						<h2 class="text-lg font-bold" style="color: var(--text-primary)">Filter tree</h2>
 					</div>
-					@FilterBuilderRows("items")
+					@FilterBuilderRows("item")
 <div class="mt-4 pt-4 border-t flex justify-end gap-2" style="border-color: var(--border);">
 						<button type="button" @click="backToCollection()" class="btn btn-secondary">Cancel</button>
 						<button type="button" @click="applyCollectionTree()" class="btn btn-primary">Apply to Collection</button>