Migrate all IPC call sites to typed tauri-specta commands.*

Replace the remaining ~155 untyped invoke() calls across stores, services,
components, and routes with the generated commands.* wrappers from
$lib/api/bindings, so every IPC call is compile-time-checked against the
command signatures.

- Register repository_get_subtitle_url and repository_get_video_download_url
  in specta_builder() and the invoke_handler; regenerate bindings.ts.
- Source duplicated wire types (AutoplaySettings, CacheConfig, Session,
  ConnectivityStatus, audio/video settings, etc.) from bindings.
- Fix two bugs surfaced by the typed wrappers:
  - VideoDownloadButton passed an un-awaited Promise as the stream URL.
  - setAutoplaySettings omitted the required userId argument.
- Update unit tests asserting the old invoke(name, args) shape.
- Remove the five param-naming guard tests; the compiler and codegen now
  enforce what they checked.

svelte-check: 0 errors. vitest: green. cargo test --lib: green.

src/lib/components/sessions/CastButton.svelte

@@ -1,7 +1,7 @@
 <!-- TRACES: UR-010 | DR-037 -->
 <script lang="ts">
   import { onMount, onDestroy } from "svelte";
-  import { invoke } from "@tauri-apps/api/core";
+  import { commands } from "$lib/api/bindings";
   import { sessions, controllableSessions, selectedSession } from "$lib/stores";
   import SessionPickerModal from "./SessionPickerModal.svelte";
 
@@ -42,18 +42,18 @@
 
     // Set initial hint based on connection state
     const hint = isConnected ? "cast_active" : "cast_discovery";
-    await invoke("sessions_set_polling_hint", { hint });
+    await commands.sessionsSetPollingHint(hint);
   });
 
   onDestroy(async () => {
     // Reset to normal polling when component unmounts
-    await invoke("sessions_set_polling_hint", { hint: "normal" });
+    await commands.sessionsSetPollingHint("normal");
   });
 
   // Update polling hint when connection state changes
   $effect(() => {
     const hint = isConnected ? "cast_active" : "cast_discovery";
-    invoke("sessions_set_polling_hint", { hint });
+    commands.sessionsSetPollingHint(hint);
   });
 
   const isConnected = $derived($selectedSession !== null);