fix(plugins): trust platform certificates

Use the operating system trust store and Windows proxy settings while keeping TLS verification enabled. Add retryable registry errors with copyable diagnostics.\n\nRefs #563

src/app/mod.rs

@@ -524,6 +524,14 @@ pub(super) struct OpenCADStudio {
     loaded_plugin_ids: rustc_hash::FxHashSet<String>,
     /// Curated plugin registry fetched from the OpenCADStudio repo.
     plugin_registry: Vec<crate::plugin::external::RegistryEntry>,
+    /// True while the curated registry request is in flight.
+    plugin_registry_loading: bool,
+    /// Last curated-registry request error. Kept separate from general
+    /// marketplace status so the UI can show a friendly retry card and retain
+    /// copyable technical details.
+    plugin_registry_error: Option<String>,
+    /// Whether the registry error card exposes its raw diagnostic text.
+    plugin_registry_error_details_open: bool,
     /// User-linked plugin source repos (`owner/repo`) beyond the curated list.
     plugin_repos: Vec<String>,
     /// Add-repository text field in the Plugin Manager.
@@ -2076,6 +2084,12 @@ pub enum Message {
     PluginRepoRemove(String),
     /// The curated registry was fetched.
     PluginRegistryFetched(Result<Vec<crate::plugin::external::RegistryEntry>, String>),
+    /// Retry the curated registry request after a connection failure.
+    PluginRegistryRetry,
+    /// Expand or collapse raw registry error details.
+    PluginRegistryErrorDetailsToggle,
+    /// Copy registry URL, platform, version, and raw error details.
+    PluginRegistryCopyDiagnostics,
     /// Patreon supporters fetched at boot for the Start page (name, pledge cents).
     PatronsFetched(Result<Vec<(String, i64)>, String>),
     /// Tutorial-playlist videos fetched at boot for the Start page.
@@ -2609,6 +2623,9 @@ impl OpenCADStudio {
             external_plugins: Vec::new(),
             loaded_plugin_ids: rustc_hash::FxHashSet::default(),
             plugin_registry: Vec::new(),
+            plugin_registry_loading: false,
+            plugin_registry_error: None,
+            plugin_registry_error_details_open: false,
             plugin_repos: Vec::new(),
             plugin_repo_input: String::new(),
             plugin_search_input: String::new(),

src/app/update/mod.rs

@@ -3956,6 +3956,9 @@ impl OpenCADStudio {
                 // Fetch the curated registry and release lists for linked repos.
                 #[cfg(not(target_arch = "wasm32"))]
                 {
+                    self.plugin_registry_loading = true;
+                    self.plugin_registry_error = None;
+                    self.plugin_registry_error_details_open = false;
                     let mut tasks = vec![self.fetch_registry_task()];
                     let release_repos: rustc_hash::FxHashSet<String> = self
                         .plugin_repos
@@ -4074,6 +4077,9 @@ impl OpenCADStudio {
                 Task::none()
             }
             Message::PluginRegistryFetched(Ok(entries)) => {
+                self.plugin_registry_loading = false;
+                self.plugin_registry_error = None;
+                self.plugin_registry_error_details_open = false;
                 // Fetch releases for every curated repo so the dropdowns fill in.
                 #[cfg(not(target_arch = "wasm32"))]
                 {
@@ -4112,7 +4118,41 @@ impl OpenCADStudio {
                 }
             }
             Message::PluginRegistryFetched(Err(e)) => {
-                self.marketplace_status = format!("Registry: {e}");
+                self.plugin_registry_loading = false;
+                self.plugin_registry_error = Some(e);
+                self.plugin_registry_error_details_open = false;
+                Task::none()
+            }
+            Message::PluginRegistryRetry => {
+                #[cfg(not(target_arch = "wasm32"))]
+                {
+                    self.plugin_registry_loading = true;
+                    self.plugin_registry_error = None;
+                    self.plugin_registry_error_details_open = false;
+                    return self.fetch_registry_task();
+                }
+                #[cfg(target_arch = "wasm32")]
+                Task::none()
+            }
+            Message::PluginRegistryErrorDetailsToggle => {
+                if self.plugin_registry_error.is_some() {
+                    self.plugin_registry_error_details_open =
+                        !self.plugin_registry_error_details_open;
+                }
+                Task::none()
+            }
+            Message::PluginRegistryCopyDiagnostics => {
+                #[cfg(not(target_arch = "wasm32"))]
+                if let Some(error) = &self.plugin_registry_error {
+                    return iced::clipboard::write(format!(
+                        "Open CAD Studio v{}\nOS: {}\nArchitecture: {}\nRegistry: {}\nError: {}",
+                        env!("CARGO_PKG_VERSION"),
+                        std::env::consts::OS,
+                        std::env::consts::ARCH,
+                        crate::plugin::marketplace::REGISTRY_URL,
+                        error,
+                    ));
+                }
                 Task::none()
             }
             Message::PatronsFetched(Ok(names)) => {

src/app/view/modal.rs

@@ -78,6 +78,9 @@ impl OpenCADStudio {
                     &self.loaded_plugin_ids,
                     crate::ui::window::plugin_manager::MarketView {
                         registry: &self.plugin_registry,
+                        registry_loading: self.plugin_registry_loading,
+                        registry_error: self.plugin_registry_error.as_deref(),
+                        registry_error_details_open: self.plugin_registry_error_details_open,
                         input: &self.plugin_repo_input,
                         search: &self.plugin_search_input,
                         repos: &self.plugin_repos,