feat(playlist): auto-detect import method that parses pasted provider messages

Adds a deterministic parser (detectProviderImportCandidates in
libs/shared/interfaces) that scans a pasted provider message for URLs, MAC
addresses, and labeled credentials/identity fields (username, password,
serial, device IDs, signatures), classifies the source as Xtream, Stalker,
or an M3U link/body, and returns ranked candidates. Every extracted value is
a verbatim substring or a canonical form from an existing shared normalizer;
detection only proposes — the existing forms and their behavioral probes
(portal discovery, connection test) stay authoritative.

The Add playlist dialog gains a sixth "Auto-detect" method with a textarea
that runs the parser on every edit and renders candidate cards; picking one
switches to the matching import form with the fields prefilled.

Detection runs fully locally; pasted text never leaves the app.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JE1De2dfyRZMYh4H2iGXb4

libs/workspace/shell/util/src/lib/workspace-shell-actions.ts

@@ -9,7 +9,8 @@ export type WorkspacePlaylistType =
     | 'url'
     | 'text'
     | 'file'
-    | 'stalker';
+    | 'stalker'
+    | 'auto';
 export type PlaylistCategory = 'm3u' | 'xtream' | 'stalker';
 export type M3uSubType = 'url' | 'file' | 'text';