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/services/preload.test.ts

@@ -6,6 +6,20 @@
 
 import { describe, it, expect, beforeEach, vi } from "vitest";
 import { preloadUpcomingTracks, updateCacheConfig, getCacheConfig } from "./preload";
+import type { CacheConfig } from "$lib/api/bindings";
+
+// updateCacheConfig now takes a full CacheConfig (matches the backend command)
+function makeConfig(overrides: Partial<CacheConfig> = {}): CacheConfig {
+  return {
+    queuePrecacheEnabled: true,
+    queuePrecacheCount: 5,
+    albumAffinityEnabled: false,
+    albumAffinityThreshold: 0.75,
+    storageLimit: 2 * 1024 * 1024 * 1024,
+    wifiOnly: false,
+    ...overrides,
+  };
+}
 
 vi.mock("@tauri-apps/api/core", () => ({
   invoke: vi.fn(async (command: string, args?: any) => {
@@ -135,10 +149,10 @@ describe("preload service", () => {
 
   describe("updateCacheConfig", () => {
     it("should update cache config", async () => {
-      const config = {
+      const config = makeConfig({
         queuePrecacheEnabled: false,
         queuePrecacheCount: 10,
-      };
+      });
 
       await expect(updateCacheConfig(config)).resolves.toBeUndefined();
     });
@@ -147,7 +161,7 @@ describe("preload service", () => {
       const { invoke } = await import("@tauri-apps/api/core");
       const invokeSpy = vi.mocked(invoke);
 
-      const config = { queuePrecacheEnabled: true };
+      const config = makeConfig({ queuePrecacheEnabled: true });
       await updateCacheConfig(config);
 
       const call = invokeSpy.mock.calls.find(
@@ -157,8 +171,8 @@ describe("preload service", () => {
       expect(call![1]).toHaveProperty("config", config);
     });
 
-    it("should support partial config updates", async () => {
-      const config = { wifiOnly: true };
+    it("should support overriding individual config options", async () => {
+      const config = makeConfig({ wifiOnly: true });
       await expect(updateCacheConfig(config)).resolves.toBeUndefined();
     });