fix(portals): absent is not empty, and every start claims the generation

Four more from review, three of them defects in last round's fixes.

The restore normalizer materialized `sourcePins: []` for archives that never
had the field, so "absent means no opinion" became "this archive says there
are no pins" and a merge cleared the user's. Absent now stays absent. My test
for that behaviour had passed for the wrong reason — it stubbed an empty pin
list, so the clear was skipped whether or not the guard worked.

`startGeneration` was claimed only by the switch path, so a plain Play, Resume
or Restart could be overtaken by a switch still awaiting its close. Every
start claims it now.

Raw and normalized tokens were paired by position, which breaks when
normalization drops a whole word: "FR: Ça" normalizes to "ca" and got handed
the raw token "FR:", sending it down the ASCII branch it cannot match from.
They are paired by normalized form instead.

And the ambiguous yearless alias (`title:dune:`) is no longer written or
retired beside a precise key — it may hold another remake's pre-enrichment
pin. It stays available when it is the only key there is, since refusing to
pin at all would be worse.

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

libs/playlist/shared/ui/src/lib/playlist-refresh-action.service.spec.ts

@@ -468,8 +468,6 @@ describe('PlaylistRefreshActionService', () => {
                 },
             ],
             playbackPositions: [],
-            // Normalized state always carries every collection, empty or not.
-            sourcePins: [],
         });
         expect(store.dispatch).toHaveBeenCalledWith(
             PlaylistActions.updatePlaylistMeta({

libs/playlist/shared/ui/src/lib/recent-playlists/recent-playlists.component.spec.ts

@@ -555,8 +555,6 @@ describe('RecentPlaylistsComponent busy state', () => {
                 },
             ],
             playbackPositions: [],
-            // Normalized state always carries every collection, empty or not.
-            sourcePins: [],
         });
         expect(router.navigate).toHaveBeenCalledWith([
             '/workspace',