Resolves the 5 /code-review high findings on this branch:
- a11y sweep: extend aria-label to the remaining icon-only Plex card buttons the
first pass missed — PlexPosterCard Info, SeasonCard watched-toggle + add-season
(EpisodeCard already had them). "Fix a principle everywhere, in one sweep."
- new shared lib/parseId.ts `parsePositiveIntId`, used by BOTH readSelectedId
(now guarding the stored ?pl fallback the same as the URL — was unguarded) and
plexSubUrl's ?v=playlist decode; removes the hand-duplicated guard.
- PAGE_KEY exported from navigationInit and imported by NavigationProvider (was
defined in both).
- hoist a `watchedLabel` const per card so title + aria-label can't drift.
+8 tests (parseId unit + guarded-stored ?pl); full FE gate green (tsc/eslint/
prettier/knip, 317 vitest).
Move `type Sub` + `PLEX_SUB_URL` out of the 538-line PlexBrowse into a small
plexSubUrl.ts so the encode/decode round-trip and its guards can be unit-tested
without dragging the component (and its lazy hls.js player) into the test graph.
Pure code motion — PlexBrowse imports the two symbols; the `SubviewUrl` import
moves with them.
Tests lock: encode of each bookmarkable kind, grid/player → null, encode→decode
identity, a person name containing ':' round-tripping, and the decode guards
(positive-integer playlist id; season needs both ids; non-empty show/info/person
arg; unknown kind/garbage → null).
12 tests; full FE gate green (tsc/eslint/prettier/knip).
peter