feat: add OpenCode Go provider and support for custom models

- Introduced OpenCode Go provider with relevant configurations.
- Enhanced model management by allowing users to add and delete custom models.
- Updated UI components to support model selection for image types.
- Adjusted sidebar visibility to include image media kinds.

src/lib/localDb.js

@@ -44,6 +44,7 @@ function cloneDefaultData() {
     providerNodes: [],
     proxyPools: [],
     modelAliases: {},
+    customModels: [],
     mitmAlias: {},
     combos: [],
     apiKeys: [],
@@ -515,6 +516,33 @@ export async function deleteModelAlias(alias) {
   await safeWrite(db);
 }
 
+// Custom models — user-added models with explicit type (llm/image/tts/embedding/...)
+export async function getCustomModels() {
+  const db = await getDb();
+  return db.data.customModels || [];
+}
+
+export async function addCustomModel({ providerAlias, id, type = "llm", name }) {
+  const db = await getDb();
+  if (!db.data.customModels) db.data.customModels = [];
+  const exists = db.data.customModels.some(
+    (m) => m.providerAlias === providerAlias && m.id === id && (m.type || "llm") === type
+  );
+  if (exists) return false;
+  db.data.customModels.push({ providerAlias, id, type, name: name || id });
+  await safeWrite(db);
+  return true;
+}
+
+export async function deleteCustomModel({ providerAlias, id, type = "llm" }) {
+  const db = await getDb();
+  if (!db.data.customModels) return;
+  db.data.customModels = db.data.customModels.filter(
+    (m) => !(m.providerAlias === providerAlias && m.id === id && (m.type || "llm") === type)
+  );
+  await safeWrite(db);
+}
+
 export async function getMitmAlias(toolName) {
   const db = await getDb();
   const all = db.data.mitmAlias || {};