docs: flip stale PINCHFLAT output-path checkbox (implemented Batch 26)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ROADMAP-PINCHFLAT.md

@@ -151,10 +151,15 @@ Turn a `MediaItem` into a real per-item download that lands in `Channel / Playli
       directory chars (`< > : " / \ | ? *`, trailing dots/spaces, reserved names like `CON`).
       Critical because `--restrict-filenames` only sanitizes the *filename* yt-dlp generates,
       not the directory segments AeroFetch constructs from channel/playlist names.
-- [ ] **Output-path setting.** A new Settings → Downloads field for the folder layout, defaulting
+- [x] **Output-path setting.** A new Settings → Downloads field for the folder layout, defaulting
       to `Channel / Playlist / Title`, with the raw yt-dlp `-o` template exposed for power users
       (parallels how Phase C exposed raw extra args). Keeps the existing flat
-      `filenameTemplate` as the default for non-collection downloads.
+      `filenameTemplate` as the default for non-collection downloads. *Implemented (Batch 26):
+      `Settings.collectionOutputTemplate` — blank = the built-in `Channel/Playlist/NNN - Title`
+      layout; a raw yt-dlp `-o` template overrides it for collection downloads.
+      `collectionOutputTemplate()` (buildArgs) takes the optional custom template; the zod schema
+      validates it as a safe relative template; surfaced as the "Collection folder layout" field in
+      Settings → Downloads → Filenames. A Media Profile can override it per-source (Batch 27).*
 - [x] **"Media Profile" = named download preset.** Pinchflat bundles quality + subs + output
       template into a reusable Profile. Implemented: a `MediaProfile` = named bundle of
       `{ kind, quality, options, outputTemplate, extraArgs }` a Source points at via `Source.profileId`.