feat(01-03): API routers (calendar, generate, export, settings) e wiring main.py

- schemas/settings.py: Settings pydantic model con api_key, llm_model, nicchie_attive, tono
- routers/calendar.py: POST /api/calendar/generate, GET /api/calendar/formats
- routers/generate.py: POST /api/generate/bulk (202 + job_id), GET /job/{job_id}/status (polling), GET /job/{job_id}, POST /single
- routers/export.py: GET /api/export/{job_id}/csv (originale), POST /api/export/{job_id}/csv (modifiche inline)
- routers/settings.py: GET /api/settings/status (api_key_configured), GET /api/settings, PUT /api/settings
- main.py: include_router x4 PRIMA di SPAStaticFiles, copia prompt default al primo avvio

backend/main.py

@@ -5,6 +5,7 @@ It is passed only via Uvicorn's --root-path flag at runtime to avoid the
 double-path bug (Pitfall #4).
 """
 
+import shutil
 from contextlib import asynccontextmanager
 from pathlib import Path
 
@@ -13,6 +14,7 @@ from fastapi.responses import FileResponse
 from fastapi.staticfiles import StaticFiles
 
 from backend.config import CAMPAIGNS_PATH, CONFIG_PATH, OUTPUTS_PATH, PROMPTS_PATH
+from backend.routers import calendar, export, generate, settings
 
 
 # ---------------------------------------------------------------------------
@@ -35,11 +37,27 @@ class SPAStaticFiles(StaticFiles):
 # Startup / shutdown lifecycle
 # ---------------------------------------------------------------------------
 
+# Directory dei prompt di default (inclusa nel source)
+_DEFAULT_PROMPTS_DIR = Path(__file__).parent / "data" / "prompts"
+
+
 @asynccontextmanager
 async def lifespan(app: FastAPI):
-    """Create required data directories on startup if they do not exist."""
+    """Create required data directories on startup if they do not exist.
+
+    Also copies default prompts to PROMPTS_PATH on first run (when empty).
+    """
+    # Crea directory dati
     for directory in (PROMPTS_PATH, OUTPUTS_PATH, CAMPAIGNS_PATH, CONFIG_PATH):
         directory.mkdir(parents=True, exist_ok=True)
+
+    # Copia prompt default al primo avvio (se PROMPTS_PATH è vuota)
+    if _DEFAULT_PROMPTS_DIR.exists() and not any(PROMPTS_PATH.glob("*.txt")):
+        for prompt_file in _DEFAULT_PROMPTS_DIR.glob("*.txt"):
+            dest = PROMPTS_PATH / prompt_file.name
+            if not dest.exists():
+                shutil.copy2(prompt_file, dest)
+
     yield
     # Nothing to clean up on shutdown
 
@@ -68,6 +86,13 @@ async def health() -> dict:
     return {"status": "ok"}
 
 
+# Include all API routers — ORDER MATTERS (registered before SPA catch-all)
+app.include_router(calendar.router)
+app.include_router(generate.router)
+app.include_router(export.router)
+app.include_router(settings.router)
+
+
 # ---------------------------------------------------------------------------
 # SPA catch-all mount (MUST be last — catches everything not matched above)
 # ---------------------------------------------------------------------------