feat(frontend): simplify setup to 3 fields + improve loading messages

- Removed DASHSCOPE_API_KEY and SMTP_PASSWORD from setup form and
  settings page — only STUID, UISPSW, and GitHub PAT are needed.
- Granular loading messages: Connecting → Deriving key → Downloading
  index → Shard i/n — so users know what stage the spinner is at.

Author: LeafCreeper

frontend/index.html

@@ -221,16 +221,6 @@ <h2 class="text-xl font-bold text-gray-800 mb-1">iCourse Subscriber</h2>
         <input x-model="setup.uispsw" type="password"
                class="w-full border rounded-lg px-3 py-2 text-sm focus:ring-2 focus:ring-blue-300 focus:outline-none">
       </div>
-      <div>
-        <label class="block text-xs text-gray-500 mb-1">DASHSCOPE_API_KEY</label>
-        <input x-model="setup.dashscope" type="password" placeholder="sk-..."
-               class="w-full border rounded-lg px-3 py-2 text-sm font-mono focus:ring-2 focus:ring-blue-300 focus:outline-none">
-      </div>
-      <div>
-        <label class="block text-xs text-gray-500 mb-1">SMTP_PASSWORD (QQ authorization code)</label>
-        <input x-model="setup.smtp" type="password"
-               class="w-full border rounded-lg px-3 py-2 text-sm font-mono focus:ring-2 focus:ring-blue-300 focus:outline-none">
-      </div>
 
       <!-- Advanced -->
       <details class="text-sm">
@@ -533,8 +523,6 @@ <h2 class="text-lg font-bold text-gray-800 mb-4">Credentials</h2>
         {key: 'token', label: 'GitHub PAT'},
         {key: 'stuid', label: 'STUID'},
         {key: 'uispsw', label: 'UISPSW'},
-        {key: 'dashscope', label: 'DASHSCOPE_API_KEY'},
-        {key: 'smtp', label: 'SMTP_PASSWORD'}
       ]" :key="field.key">
         <div>
           <label class="block text-xs text-gray-500 mb-1" x-text="field.label"></label>

frontend/js/app.js

@@ -207,7 +207,7 @@ document.addEventListener("alpine:init", () => {
     detailView: "summary",
     searchQuery: "", searchResults: [],
     commitSha: null,
-    setup: { token: "", stuid: "", uispsw: "", dashscope: "", smtp: "" },
+    setup: { token: "", stuid: "", uispsw: "" },
     setupError: "", setupTesting: false,
     settingsForm: {}, showSecrets: {},
     exportDialogOpen: false, exportSelection: {}, exportingPdf: false,
@@ -240,23 +240,27 @@ document.addEventListener("alpine:init", () => {
     async _loadDB(creds) {
       this.view = "loading"; this.error = null;
       try {
-        this.loadingMsg = "Checking for updates...";
+        this.loadingMsg = "Connecting to GitHub API...";
         var manifest = await ICS.github.fetchShardManifest(
           this.repoOwner, this.repoName, this.dataBranch, creds.token,
         );
         this.commitSha = manifest.commitSha;
 
         if (manifest.format === "sharded") {
+          this.loadingMsg = "Deriving decryption key...";
           var pw = await ICS.crypto.buildPasswordV2(creds);
+
+          this.loadingMsg = "Downloading + decrypting shard index...";
           var self = this;
           await _loadFromShardManifest(
             manifest, this.repoOwner, this.repoName, pw, creds.token,
             function (i, n, name) {
-              self.loadingMsg = "Loading shard " + i + "/" + n + " (" + name + ")...";
+              self.loadingMsg = "Shard " + i + "/" + n
+                + " — downloading + decrypting (" + name + ")...";
             },
           );
         } else {
-          this.loadingMsg = "Loading legacy database...";
+          this.loadingMsg = "Downloading + decrypting legacy database...";
           await _loadFromLegacyBlob(
             manifest, this.repoOwner, this.repoName, creds, creds.token,
           );
@@ -507,7 +511,7 @@ document.addEventListener("alpine:init", () => {
       localStorage.removeItem(_LS + "settings");
       indexedDB.deleteDatabase(_idbName);
       this.view = "setup";
-      this.setup = { token: "", stuid: "", uispsw: "", dashscope: "", smtp: "" };
+      this.setup = { token: "", stuid: "", uispsw: "" };
     },
 
     // ── Subscriptions editor ────────────────────────────────────────