Fix project rename, remove confirmation, and auth mode change bugs

- Add double-click-to-rename on project names in the sidebar
- Replace window.confirm() with inline React confirmation for project
  removal (confirm dialog didn't block in Tauri webview)
- Add serde(default) to skip_serializing fields in Rust models so
  deserialization doesn't fail when frontend omits secret fields

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

app/src-tauri/src/models/project.rs

@@ -35,7 +35,7 @@ pub struct Project {
     pub bedrock_config: Option<BedrockConfig>,
     pub allow_docker_access: bool,
     pub ssh_key_path: Option<String>,
-    #[serde(skip_serializing)]
+    #[serde(skip_serializing, default)]
     pub git_token: Option<String>,
     pub git_user_name: Option<String>,
     pub git_user_email: Option<String>,
@@ -100,14 +100,14 @@ impl Default for BedrockAuthMethod {
 pub struct BedrockConfig {
     pub auth_method: BedrockAuthMethod,
     pub aws_region: String,
-    #[serde(skip_serializing)]
+    #[serde(skip_serializing, default)]
     pub aws_access_key_id: Option<String>,
-    #[serde(skip_serializing)]
+    #[serde(skip_serializing, default)]
     pub aws_secret_access_key: Option<String>,
-    #[serde(skip_serializing)]
+    #[serde(skip_serializing, default)]
     pub aws_session_token: Option<String>,
     pub aws_profile: Option<String>,
-    #[serde(skip_serializing)]
+    #[serde(skip_serializing, default)]
     pub aws_bearer_token: Option<String>,
     pub model_id: Option<String>,
     pub disable_prompt_caching: bool,