Add container registry pull, image source settings, and global AWS config

Support pulling images from registry (default: repo.anhonesthost.net/cybercovellc/triple-c/triple-c-sandbox:latest),
local builds, or custom images via a new settings UI. Add global AWS configuration
(config path auto-detect, profile picker, region) that serves as defaults overridable
per-project for Bedrock auth.

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

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

@@ -1,11 +1,55 @@
 use serde::{Deserialize, Serialize};
 
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+#[serde(rename_all = "snake_case")]
+pub enum ImageSource {
+    Registry,
+    LocalBuild,
+    Custom,
+}
+
+impl Default for ImageSource {
+    fn default() -> Self {
+        Self::Registry
+    }
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct GlobalAwsSettings {
+    #[serde(default)]
+    pub aws_config_path: Option<String>,
+    #[serde(default)]
+    pub aws_profile: Option<String>,
+    #[serde(default)]
+    pub aws_region: Option<String>,
+}
+
+impl Default for GlobalAwsSettings {
+    fn default() -> Self {
+        Self {
+            aws_config_path: None,
+            aws_profile: None,
+            aws_region: None,
+        }
+    }
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct AppSettings {
+    #[serde(default)]
     pub default_ssh_key_path: Option<String>,
+    #[serde(default)]
     pub default_git_user_name: Option<String>,
+    #[serde(default)]
     pub default_git_user_email: Option<String>,
+    #[serde(default)]
     pub docker_socket_path: Option<String>,
+    #[serde(default)]
+    pub image_source: ImageSource,
+    #[serde(default)]
+    pub custom_image_name: Option<String>,
+    #[serde(default)]
+    pub global_aws: GlobalAwsSettings,
 }
 
 impl Default for AppSettings {
@@ -15,6 +59,9 @@ impl Default for AppSettings {
             default_git_user_name: None,
             default_git_user_email: None,
             docker_socket_path: None,
+            image_source: ImageSource::default(),
+            custom_image_name: None,
+            global_aws: GlobalAwsSettings::default(),
         }
     }
 }