feat: analysis providers, settings UI, song search, WAV duration fix

- Multi-provider AI analysis (Anthropic, OpenAI, Ollama, Algorithmic)
- server-only guards on all provider files; client bundle fix
- /settings page with provider status, Ollama model picker, preferences
- Song search box on /analyze replacing raw MBID input (debounced, keyboard nav)
- Auto-register song via MusicBrainz on POST /api/tracks (no more 404)
- Fix WAV duration bug: last section songEnd was double-counting elapsed time
- Registry sync comment updated for self-hosted HTTPS git servers

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/settings/PreferencesPanel.tsx

@@ -0,0 +1,79 @@
+"use client";
+
+import { useState, useEffect } from "react";
+
+const PROVIDER_KEY = "clicktrack_analysis_provider";
+const MODEL_KEY = "clicktrack_ollama_model";
+
+export default function PreferencesPanel() {
+  const [rememberProvider, setRememberProvider] = useState(true);
+  const [rememberModel, setRememberModel] = useState(true);
+  const [cleared, setCleared] = useState(false);
+
+  useEffect(() => {
+    // Reflect current state: if the keys exist, persistence is active
+    const hasProvider = localStorage.getItem(PROVIDER_KEY) !== null;
+    const hasModel = localStorage.getItem(MODEL_KEY) !== null;
+    setRememberProvider(hasProvider);
+    setRememberModel(hasModel);
+  }, []);
+
+  function handleToggleProvider(on: boolean) {
+    setRememberProvider(on);
+    if (!on) {
+      localStorage.removeItem(PROVIDER_KEY);
+    }
+  }
+
+  function handleToggleModel(on: boolean) {
+    setRememberModel(on);
+    if (!on) {
+      localStorage.removeItem(MODEL_KEY);
+    }
+  }
+
+  function handleClear() {
+    localStorage.removeItem(PROVIDER_KEY);
+    localStorage.removeItem(MODEL_KEY);
+    setRememberProvider(false);
+    setRememberModel(false);
+    setCleared(true);
+    setTimeout(() => setCleared(false), 3000);
+  }
+
+  return (
+    <div className="space-y-4">
+      <label className="flex items-center gap-3 cursor-pointer">
+        <input
+          type="checkbox"
+          checked={rememberProvider}
+          onChange={(e) => handleToggleProvider(e.target.checked)}
+          className="accent-green-500 w-4 h-4"
+        />
+        <span className="text-sm text-zinc-300">Remember my last provider selection</span>
+      </label>
+
+      <label className="flex items-center gap-3 cursor-pointer">
+        <input
+          type="checkbox"
+          checked={rememberModel}
+          onChange={(e) => handleToggleModel(e.target.checked)}
+          className="accent-green-500 w-4 h-4"
+        />
+        <span className="text-sm text-zinc-300">Remember my last Ollama model</span>
+      </label>
+
+      <div className="pt-1">
+        <button
+          onClick={handleClear}
+          className="rounded-lg border border-zinc-700 px-4 py-2 text-sm text-zinc-400 hover:border-zinc-500 hover:text-zinc-200 transition-colors"
+        >
+          Clear saved preferences
+        </button>
+        {cleared && (
+          <span className="ml-3 text-sm text-green-400">Preferences cleared.</span>
+        )}
+      </div>
+    </div>
+  );
+}