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/remote-agent/remote-runtime-installation-manager.test.ts

@@ -236,7 +236,10 @@ const registry: AgentReleaseKeyRegistry = {
   formatVersion: 1,
   keys: [{
     keyId: 'test-key',
-    publicKeySpkiBase64: 'AAAA',
+    publicKeySpkiBase64: Buffer.from(
+      '302a300506032b6570032100000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f',
+      'hex'
+    ).toString('base64'),
     environment: 'test'
   }],
   revocations: []