M4 wrap — playlist browse + addon settings + upstream PR-77 notes

Sidecar Playlist op via rustypipe playlist(). Returns playlist metadata
block (id, name, channel, video_count) + items array. Verified live
against LTT's 'Consumer Advocacy' (PL8mG-RkN2uTzwoF72GqeqAJMI-N7scqtI):
returns the single video with full metadata.

Addon ?action=playlist&id=PL... lists items via _add_video_items reuse.
Verified via Files.GetDirectory JSON-RPC.

resources/settings.xml gains a 'dash_enabled' toggle (boolean, default
off). main.py checks ADDON.getSettingBool('dash_enabled') OR the
TORTTUBE_DASH env fallback before attempting the DASH path. Toggle via
Kodi Settings → Add-on settings → torttube, OR via
Addons.SetSettings JSON-RPC.

docs/upstream.md: filed a 'watching' entry for rustypipe PR #77
(Schmiddiii's late-May YouTube parsing fixes) with our independent
test data — player(), search(), and channel_videos() all still work
against current YouTube on 0.11.4, suggesting the PR fixes code paths
torttube doesn't yet exercise. Endorsement comment pending: gated on
creating a Sulkta-Coop codeberg account.

Observation from kodi.log: plugin.video.youtube successfully parsed a
DASH MPD with 26 streams via inputstream.adaptive on this same Pi —
proves DASH is solvable on our setup, just need to match the URL
pattern they use. M7 stabilization carrying forward.

Addon version 0.0.9.

MILESTONES.md

@@ -46,8 +46,10 @@
 - [x] channel browse → `{"op":"channel_videos","id":"…"}` — verified 30
       videos returned for LTT's UCXuqSBlHAE6Xw-yeJA0Tunw via JSON-RPC
 - [x] context-menu entry on every result: "Go to <channel>" → channel listing
-- [ ] playlist browse → `{"op":"playlist","id":"…"}`
-- [ ] paginated results (currently capped at limit=30/50)
+- [x] playlist browse → `{"op":"playlist","id":"…"}` — verified with
+      LTT's "Consumer Advocacy" playlist, returns playlist metadata
+      (name, channel, video_count) + items array
+- [ ] paginated results (currently capped at limit=30/50/100)
 - [ ] search history
 
 ## M5 — SponsorBlock skipping [DONE]