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

@@ -970,8 +970,8 @@ private void loadModeOptions() {
       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("Workspace name is empty for custom agent: "
+              + mode.getDisplayName() + " (ID: " + mode.getId() + ")");
           continue;
         }
         options.add(workspaceName + ": " + mode.getDisplayName());
@@ -1086,14 +1086,18 @@ private String getWorkspaceNameForMode(CustomChatMode mode) {
       List<WorkspaceFolder> workspaceFolders = WorkspaceUtils.listWorkspaceFolders();
       if (workspaceFolders != null) {
         for (WorkspaceFolder folder : workspaceFolders) {
-          Path folderPath = Paths.get(java.net.URI.create(folder.getUri()));
-          if (modePath.startsWith(folderPath)) {
-            return folder.getName();
+          try {
+            Path folderPath = Paths.get(java.net.URI.create(folder.getUri()));
+            if (modePath.startsWith(folderPath)) {
+              return folder.getName();
+            }
+          } catch (Exception folderEx) {
+            CopilotCore.LOGGER.error("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("Failed to get workspace name for mode id=" + mode.getId(), e);
     }
     return "";
   }