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/shared/ipc.ts

@@ -70,7 +70,7 @@ export const IpcChannels = {
   /** main → renderer push channel: a URL handed to AeroFetch from outside the app
    *  (the aerofetch:// protocol, or a .url file via Explorer's "Send to" menu) */
   externalUrl: 'app:external-url',
-  // --- Sources & media-manager indexing (Pinchflat-style, see ROADMAP-PINCHFLAT.md) ---
+  // --- Sources & media-manager indexing (Pinchflat-style) ---
   sourcesList: 'sources:list',
   sourceIndex: 'sources:index',
   sourceReindex: 'sources:reindex',
@@ -433,8 +433,8 @@ export interface ProbeResult {
 }
 
 /**
- * Media-manager folder context for a collection download (see ROADMAP-PINCHFLAT.md
- * Phase G). When present on a StartDownloadOptions, the file is filed into
+ * Media-manager folder context for a collection download. When present on a
+ * StartDownloadOptions, the file is filed into
  * `<outputDir>/<channel>/<playlist>/<NNN> - <title>.<ext>` instead of the flat
  * filenameTemplate. The directory segments are sanitized for Windows at argv-build
  * time, and `index` (the 1-based playlist position from the persisted MediaItem)
@@ -864,7 +864,7 @@ export interface BackupImportResult {
 }
 
 // --- Sources & media-manager indexing (Pinchflat-style) ---------------------
-// See ROADMAP-PINCHFLAT.md. A Source (channel/playlist) is indexed once into a
+// A Source (channel/playlist) is indexed once into a
 // persisted list of MediaItem records. When the user downloads pending items,
 // all selected entries are enqueued at once — add a batch cap here if large
 // channel queues (thousands of items) cause performance issues (M33).