feat(ai): Phase 3 — text generation popup on WYSIWYG editors

Third and final phase of the AI feature. A SparklesIcon button is added to every Tiptap WYSIWYG editor (invoice notes, email body compose, note templates — ~6 places where RichEditor is used) that opens a modal with a prompt input, optional 'use current content as context' toggle, preview area, and Insert / Replace / Regenerate actions.

**Backend (thin)** — AiTextGenerationService is stateless: resolve config → check text_generation_enabled → instantiate driver → call textCompletion() with a system-prompt-wrapped user instruction. The system prompt is terse and opinionated: 'Return only the requested text. No preamble, no explanation, no markdown code fences.' When context is provided, it's included as a separate framed block ('Context (current content the user is working with):') so the model knows it's operating on existing copy.

**GenerationController** — POST /api/v1/ai/generate with {prompt, context?}. Validates prompt required (max 4000 chars) and context optional (max 20000 chars). Rate-limited via the same 'ai' RateLimiter from Phase 2 (30/min per user/company). Gated by 'use ai' Bouncer ability + AiConfigurationService resolution. Returns {text} on success or {error, message} with 422 on any AiException.

**Frontend modal (AiTextGenerationModal.vue)** — mounted globally in CompanyLayout when bootstrap reports ai.enabled && text_generation_enabled. Uses the existing modalStore pattern: self-registers on componentName='AiTextGenerationModal'. Modal state includes prompt, useContext toggle, generatedText preview. Callers (currently RichEditor) pass onInsert/onReplace callbacks via modalStore.data; the modal invokes them with the final text and closes — it knows nothing about tiptap or ProseMirror.

**RichEditor integration** — the Sparkles toolbar button is pushed onto the existing editorButtons ref at setup time, gated on globalStore.ai.enabled && text_generation_enabled. The button opens the modal with the editor's current getHTML() as context and callbacks that use the tiptap chain API: insertContent for Insert, selectAll().deleteSelection().insertContent for Replace. No reactivity on the flag check — it's set once at bootstrap and doesn't change during a session.

**Tests** (7 new) — AiGenerationTest with a dedicated TextGenDriver test double that tracks the exact prompt passed to textCompletion(). Covers: happy path, context inclusion/omission, AI globally disabled rejection, text_generation role disabled rejection, prompt/context length validation, response whitespace trimming.

395 tests pass (was 388, +7 new). Pint clean. npm run build clean. The AI feature is now complete end-to-end: provider configuration (Phase 1), chat assistant with DB tool-calling (Phase 2), and text generation popup (Phase 3).

app/Http/Controllers/Company/Ai/GenerationController.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace App\Http\Controllers\Company\Ai;
+
+use App\Http\Controllers\Controller;
+use App\Services\Ai\AiTextGenerationService;
+use App\Support\Ai\AiException;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+use Illuminate\Validation\ValidationException;
+
+class GenerationController extends Controller
+{
+    public function __construct(
+        private readonly AiTextGenerationService $generator,
+    ) {}
+
+    /**
+     * One-shot text generation for the WYSIWYG popup.
+     *
+     * Stateless — nothing is persisted. Each call is fully self-contained.
+     * Rate-limited via the shared 'ai' limiter so a stuck client can't
+     * hammer the provider.
+     *
+     * @throws ValidationException
+     */
+    public function __invoke(Request $request): JsonResponse
+    {
+        $this->authorize('use ai');
+
+        $validated = $this->validate($request, [
+            'prompt' => 'required|string|max:4000',
+            'context' => 'nullable|string|max:20000',
+        ]);
+
+        try {
+            $text = $this->generator->generate(
+                (int) $request->header('company'),
+                $validated['prompt'],
+                $validated['context'] ?? null,
+            );
+        } catch (AiException $e) {
+            return response()->json([
+                'error' => $e->errorKey,
+                'message' => $e->getMessage(),
+            ], 422);
+        }
+
+        return response()->json([
+            'text' => $text,
+        ]);
+    }
+}