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/library/AlbumDownloadButton.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
   import { downloads } from "$lib/stores/downloads";
   import { auth } from "$lib/stores/auth";
-  import { invoke } from "@tauri-apps/api/core";
+  import { commands } from "$lib/api/bindings";
   import type { MediaItem } from "$lib/api/types";
 
   interface Props {
@@ -89,18 +89,14 @@
         const downloadIds = await downloads.downloadAlbum(albumId, userId, basePath);
 
         // Get target directory for downloads
-        const targetDir = await invoke<string>("storage_get_path");
+        const targetDir = await commands.storageGetPath();
 
         // Start each queued track download
         for (let i = 0; i < tracks.length && i < downloadIds.length; i++) {
           try {
             const streamUrl = await repo.getAudioStreamUrl(tracks[i].id);
             if (streamUrl) {
-              await invoke("start_download", {
-                downloadId: downloadIds[i],
-                streamUrl,
-                targetDir,
-              });
+              await commands.startDownload(downloadIds[i], streamUrl, targetDir);
             }
           } catch (e) {
             console.error(`Failed to start download for track ${tracks[i].id}:`, e);