feat: Implement Prompt Builder functionality in Popup and Options

- Added a new "Prompt Builder" tab in the Popup for generating AI prompts with customizable parameters.
- Introduced new state variables for managing prompt styles, personas, formats, and models.
- Enhanced the Options page to fetch and display models based on the provided API key.
- Updated the actions and types to include the new 'prompt' action and its associated parameters.
- Implemented migration logic for legacy plaintext API keys to encrypted storage.
- Updated the getSystemPrompt function to incorporate prompt parameters for better instruction generation.
- Added tests for the new functionality, including context menu entries and prompt generation logic.

tests/unit/actions.test.ts

@@ -9,9 +9,12 @@ import {
 } from '@lib/actions';
 
 describe('context-menu registry', () => {
-  it('contains 5 parents + 5x5 style children = 30 entries (parity with old loops)', () => {
-    expect(CONTEXT_MENU_ENTRIES).toHaveLength(30);
+  it('contains one parent per action + style children for all actions except prompt', () => {
+    const styledActions = ACTIONS.filter((a) => a !== 'prompt');
+    expect(CONTEXT_MENU_ENTRIES).toHaveLength(ACTIONS.length + styledActions.length * CONTEXT_MENU_STYLES.length);
     expect(CONTEXT_MENU_ENTRIES.filter((e) => !e.parentId)).toHaveLength(ACTIONS.length);
+    // prompt is a single item — its parameters live in the Prompt Builder dialog
+    expect(CONTEXT_MENU_ENTRIES.filter((e) => e.parentId === 'lexai-prompt')).toHaveLength(0);
   });
 
   it('every parent precedes its children (contextMenus.create ordering)', () => {
@@ -31,6 +34,7 @@ describe('context-menu registry', () => {
       expect(parent).toMatchObject({ action, style: 'Default' });
       expect(parent!.title).toBe(`⚡ LexAI: ${ACTION_LABELS[action]}`);
 
+      if (action === 'prompt') continue; // no style children — see registry comment
       for (const style of CONTEXT_MENU_STYLES) {
         const child = findContextMenuEntry(`lexai-${action}-${style.toLowerCase()}`);
         expect(child).toMatchObject({ action, style, parentId: `lexai-${action}`, title: style });