docs: scrub dangling references to deleted roadmap docs

The ROADMAP/ROADMAP-PINCHFLAT docs were removed; this drops the now-dead
"see ROADMAP-PINCHFLAT.md" breadcrumbs (and one "the roadmap" mention)
from source comments, preserving the surrounding Pinchflat-style context.
Comment-only; typecheck (node+web) green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/main/core/indexerCore.ts

@@ -1,6 +1,6 @@
 /**
- * Pure, dependency-free core for Source indexing (Pinchflat-style media manager;
- * see ROADMAP-PINCHFLAT.md). Like buildArgs.ts / validation.ts this module imports
+ * Pure, dependency-free core for Source indexing (Pinchflat-style media
+ * manager). Like buildArgs.ts / validation.ts this module imports
  * nothing from electron or the node runtime, so its URL-classification and
  * item-merge logic can be unit-tested without spinning up Electron.
  *
@@ -222,7 +222,7 @@ export function buildMediaItems(
 
 /**
  * Merge a freshly-enumerated item list with the previously-persisted one for the
- * same source (incremental re-index; see ROADMAP-PINCHFLAT.md Phase I). The fresh
+ * same source (incremental re-index). The fresh
  * list defines the current membership/ordering, but any video already marked
  * downloaded keeps its `downloaded`/`downloadedAt`/`filePath` so a re-sync never
  * loses that state or re-downloads it. Videos that vanished from the source (now