fix: make Agent updates reliable and visible

Valid Agent packages could be rejected when packaged trusted-key JSON used CRLF, and Settings could not show whether a newer compatible Agent existed. Registry formatting is now parsed independently of cryptographic trust, and Settings reads only the signed catalog to report local and latest versions.

New installations use a credential-free local Ollama-compatible profile. The v20 migration changes only untouched historical defaults, while explicit profiles and legacy environment aliases remain compatible. Magic Notes count badges no longer shift navigation rows.

Release note: 修复 Agent 下载兼容性并在设置中显示更新状态；新安装默认连接本地模型，保留显式用户配置；魔法笔记待办数字不再改变侧栏菜单高度。

src/main/ipc.test.ts

@@ -1091,12 +1091,19 @@ describe('registerIpcHandlers SSH hosts', () => {
     }
     const agentPackageInventory = {
       checkedAt: '2030-01-01T00:00:00.000Z',
+      catalog: {
+        state: 'available',
+        checkedAt: '2030-01-01T00:00:00.000Z',
+        error: null
+      },
       entries: [
         {
           platform: 'linux',
           architecture: 'x64',
           state: 'verified',
           version: '0.11.2',
+          latestVersion: '0.11.4',
+          updateAvailable: true,
           remoteRuntimeVersion: '1.18.9',
           agentProtocol: { major: 2, minor: 0 }
         },
@@ -1105,6 +1112,8 @@ describe('registerIpcHandlers SSH hosts', () => {
           architecture: 'arm64',
           state: 'not-downloaded',
           version: null,
+          latestVersion: '0.11.4',
+          updateAvailable: false,
           remoteRuntimeVersion: null,
           agentProtocol: null
         }