feat(podcasts): the rules page retires — the collection builder IS the filter builder (item 3.4)

The smart-collection editor at /collections/:id/rules now hosts the
SAME builder island as All-Books (FilterBuilderRows — the rows markup
extracted into one shared templ both mounts render; the shared
filterBuilderExtra component). One vocabulary, one engine, one row UI;
the collection differences are exactly three: the payload is the
collection's scope (episode trees get the episode fields — books
trees hide them), Apply writes the tree to the collection (PUT
filter_tree through the validated write path), and a legacy rules
array preloads as its CONVERTED tree (RulesToFilterTree rendered
server-side) so the upgrade lands at the first Apply — read-compat
never mutates data silently.

Retired with the page: the per-rule CRUD endpoints and test-rules
(their handler bodies, routes, api-docs rows, and the dead collections.ts
island functions — the file's LIVE halves, the collection modal/navigate/
grid-refresh, stay; the dead rules half went). match-mode endpoint and
preview survive (legacy channel + the dashboard custom-section-builder,
flagged for its own migration). Contract-pin changelog documents the
deletions per the asymmetry rule.

The builder component gains collection mounts: scopeKey (the row
universe for counts/apply), data-tree prefill, treeJSON (the apply
wire with scope riding the top level), and an apply hook (the page
owns the write; All-Books never sets one). ensureReadyRule defaults to
the scope's first field instead of hardcoding author.

Tests migrated onto trees: TestSmartCollections' live-membership /
reject-mutations / include-auto / system-collection subtests now drive
TREE collections; the deleted-endpoint subtests die with them.

internal/router/collections.go

@@ -21,14 +21,10 @@ func registerCollectionsRoutes(cfg *Config) {
 	collections.DELETE("/:id/books/:bookId", cfg.CollectionHandler.RemoveBook)
 	collections.POST("/:id/books/bulk-remove", cfg.CollectionHandler.BulkRemoveBooks)
 	collections.POST("/bulk-add-books", cfg.CollectionHandler.HandleBulkAddBooks)
-	collections.POST("/test-rules", cfg.CollectionHandler.TestRules)
 	collections.POST("/preview", cfg.CollectionHandler.PreviewCollection)
 
 	// Smart collection rule CRUD (the rules builder persists through
 	// these; type follows rules presence — first rule = smart).
-	collections.POST("/:id/rules", cfg.CollectionHandler.AddRule)
-	collections.PUT("/:id/rules/:ruleId", cfg.CollectionHandler.UpdateRule)
-	collections.DELETE("/:id/rules/:ruleId", cfg.CollectionHandler.RemoveRule)
 
 	// Device shelf mapping routes
 	deviceCollections := protected.Group("/devices/:id/collections")