Choose enclosed attachments before generating; drop instant-generate

The generate form now lets the user pick which extra attachments
(basis_anhaenge) to enclose — none selected by default. Only the chosen
ones are attached, and their names are passed to the LLM so the cover
letter's "Anlagen" list and wording reflect exactly what is enclosed.

Job offers keep only "Als Bewerbung übernehmen" (draft first); the
"Übernehmen & KI-Unterlagen" button and its route are removed.

REST API: POST /applications/:id/generate accepts an optional `anlagen`
array of attachment IDs (Swagger updated).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/openapi.js

@@ -346,6 +346,13 @@ function buildOpenApiSpec(baseUrl = '') {
                   type: 'object',
                   properties: {
                     llm_notizen: { type: 'string', description: 'Freitext-Kontext für die KI (optional)' },
+                    anlagen: {
+                      type: 'array',
+                      items: { type: 'integer' },
+                      description:
+                        'IDs der zusätzlich beizulegenden statischen Anlagen (basis_anhaenge). ' +
+                        'Standard: keine. Die Auswahl erscheint auch im Anschreiben unter "Anlagen".',
+                    },
                   },
                 },
               },