fix: restore ExternalPromptService.setPromptText lost in dead-code refactor

Commit 36da0c2 (2026-02-20) removed setPromptText(String):boolean from
ExternalPromptService, treating it as dead code. It is not dead — it is
the public reflection-based API that SonarLint calls to power the
"Fix with DevoxxGenie" button. Its removal caused a silent
NoSuchMethodException, making the button appear to do nothing.

Restored:
- `project` field stored in constructor (needed to open tool window)
- `promptInputArea` field in setPromptInputArea (needed for immediate text setting)
- `setPromptText(String):boolean` — opens tool window, sets text or buffers as pendingText

Also added prominent Javadoc on both ExternalPromptService.setPromptText
and ExternalTaskService.createBacklogTask marking them NOT DEAD CODE and
referencing their SonarLint callers (DevoxxGenieBridge,
CreateDevoxxGenieTasksFromNodeAction).

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

Author: stephanj

src/main/java/com/devoxx/genie/service/ExternalPromptService.java

@@ -2,6 +2,7 @@
 
 import com.devoxx.genie.ui.component.input.PromptInputArea;
 import com.intellij.openapi.project.Project;
+import com.intellij.openapi.wm.ToolWindowManager;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -11,21 +12,45 @@
  */
 public class ExternalPromptService {
 
+    private final @NotNull Project project;
+    private @Nullable PromptInputArea promptInputArea;
     private @Nullable String pendingText;
 
     public ExternalPromptService(@NotNull Project project) {
+        this.project = project;
     }
 
     public static ExternalPromptService getInstance(@NotNull Project project) {
         return project.getService(ExternalPromptService.class);
     }
 
     public void setPromptInputArea(@Nullable PromptInputArea promptInputArea) {
+        this.promptInputArea = promptInputArea;
         if (promptInputArea != null && pendingText != null) {
             String text = pendingText;
             pendingText = null;
             promptInputArea.setText(text);
             promptInputArea.requestInputFocus();
         }
     }
+
+    /**
+     * Sets prompt text in the DevoxxGenie chat input and opens the tool window.
+     *
+     * THIS METHOD IS NOT DEAD CODE. It is the public integration API called by
+     * external plugins (e.g. SonarLint) via runtime reflection. Removing it
+     * silently breaks the "Fix with DevoxxGenie" button.
+     *
+     * @see org.sonarlint.intellij.integration.DevoxxGenieBridge (SonarLint plugin caller)
+     */
+    public boolean setPromptText(@NotNull String text) {
+        ToolWindowManager.getInstance(project).getToolWindow("DevoxxGenie").show(null);
+        if (promptInputArea != null) {
+            promptInputArea.setText(text);
+            promptInputArea.requestInputFocus();
+        } else {
+            pendingText = text;
+        }
+        return true;
+    }
 }

src/main/java/com/devoxx/genie/service/ExternalTaskService.java

@@ -31,6 +31,12 @@ public static ExternalTaskService getInstance(@NotNull Project project) {
     /**
      * Creates a backlog task. Initializes the backlog if needed.
      * Returns the created task ID (e.g., "TASK-5").
+     *
+     * THIS METHOD IS NOT DEAD CODE. It is the public integration API called by
+     * external plugins (e.g. SonarLint) via runtime reflection. Removing it
+     * silently breaks the "Create DevoxxGenie Tasks" action.
+     *
+     * @see org.sonarlint.intellij.actions.CreateDevoxxGenieTasksFromNodeAction (SonarLint plugin caller)
      */
     public String createBacklogTask(String title, String description,
                                     String priority, List<String> labels) throws IOException {