fix: isolate per-folder exception in mode picker for multi-project workspaces

In McpPreferencePage.getWorkspaceNameForMode(), the entire workspace-folder
loop was wrapped in one try-catch. If any project had a non-file:// URI
(e.g. EFS-backed sftp://, ecf:// or other custom linked resources),
Paths.get(URI.create(...)) would throw and the catch would return '' for
ALL custom modes — hiding them from the mode picker dropdown.

Move the Paths.get() call into a per-folder inner try-catch so one
bad URI only skips that folder; the loop continues for the rest.

Also add INFO/WARN diagnostic logs so future issues can be diagnosed
from workspace.log without a debugger.

Fixes: #180

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: duzitong

com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/preferences/McpPreferencePage.java

@@ -967,13 +967,16 @@ private void loadModeOptions() {
     // Add custom agents
     try {
       List<CustomChatMode> customModes = CustomChatModeManager.INSTANCE.getCustomModes();
+      CopilotCore.LOGGER.info("[McpPreferencePage] loadModeOptions: customModes.size()=" + customModes.size());
       for (CustomChatMode mode : customModes) {
         String workspaceName = getWorkspaceNameForMode(mode);
         if (workspaceName.isEmpty()) {
-          CopilotCore.LOGGER.info("Workspace name is empty for custom agent: " + mode.getDisplayName()
-              + " (ID: " + mode.getId() + ")");
+          CopilotCore.LOGGER.info("[McpPreferencePage] Workspace name is empty for custom agent: "
+              + mode.getDisplayName() + " (ID: " + mode.getId() + ")");
           continue;
         }
+        CopilotCore.LOGGER.info("[McpPreferencePage] Adding mode option: " + workspaceName + ": "
+            + mode.getDisplayName());
         options.add(workspaceName + ": " + mode.getDisplayName());
       }
     } catch (Exception e) {
@@ -1081,19 +1084,33 @@ private String extractModeIdFromSelection(String selectionText) {
   private String getWorkspaceNameForMode(CustomChatMode mode) {
     try {
       String modeId = mode.getId();
+      CopilotCore.LOGGER.info("[McpPreferencePage] getWorkspaceNameForMode: modeId=" + modeId);
       Path modePath = Paths.get(java.net.URI.create(modeId));
+      CopilotCore.LOGGER.info("[McpPreferencePage]   modePath=" + modePath);
 
       List<WorkspaceFolder> workspaceFolders = WorkspaceUtils.listWorkspaceFolders();
+      CopilotCore.LOGGER.info("[McpPreferencePage]   workspaceFolders.size()="
+          + (workspaceFolders == null ? "null" : workspaceFolders.size()));
       if (workspaceFolders != null) {
         for (WorkspaceFolder folder : workspaceFolders) {
-          Path folderPath = Paths.get(java.net.URI.create(folder.getUri()));
-          if (modePath.startsWith(folderPath)) {
-            return folder.getName();
+          CopilotCore.LOGGER.info("[McpPreferencePage]   checking folder: uri=" + folder.getUri()
+              + " name=" + folder.getName());
+          try {
+            Path folderPath = Paths.get(java.net.URI.create(folder.getUri()));
+            CopilotCore.LOGGER.info("[McpPreferencePage]     folderPath=" + folderPath
+                + " startsWith=" + modePath.startsWith(folderPath));
+            if (modePath.startsWith(folderPath)) {
+              return folder.getName();
+            }
+          } catch (Exception folderEx) {
+            CopilotCore.LOGGER.error("[McpPreferencePage]   failed to process folder uri="
+                + folder.getUri(), folderEx);
           }
         }
       }
     } catch (Exception e) {
-      CopilotCore.LOGGER.error("Failed to get workspace name for mode", e);
+      CopilotCore.LOGGER.error("[McpPreferencePage] Failed to get workspace name for mode id="
+          + mode.getId(), e);
     }
     return "";
   }