Add placeholder guide/bug-report pages, and an exclamation-mark bug icon

/guida now serves a static app/static/guida.html placeholder instead of
docs/guida-utente.md, which sidesteps the known Docker gap (docs/ was never
COPYed into the image). Added a matching /report-bug placeholder route and
pointed the navbar's bug icon at it instead of the unset GitHub issues URL,
with an outline circle + exclamation mark to match the help icon's style.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/main.py

@@ -1,7 +1,6 @@
 import asyncio
 import logging
 from contextlib import asynccontextmanager
-from pathlib import Path
 
 from fastapi import FastAPI, Request, status
 from fastapi.responses import FileResponse, JSONResponse
@@ -21,7 +20,7 @@ from app.api.routes.rounds import router as rounds_router
 from app.api.routes.users import router as users_router
 from app.api.routes.withdrawals import router as withdrawals_router
 from app.auth.routes import router as auth_router
-from app.api.errors import ApiError, http_error
+from app.api.errors import ApiError
 from app.config import settings, validate_runtime_secrets
 from app.db.base import AsyncSessionLocal
 from app.electrum.client import ElectrumClient, ElectrumEndpoint, parse_endpoints
@@ -119,22 +118,14 @@ async def admin_panel() -> FileResponse:
     return FileResponse("app/static/admin.html", headers=_NO_STORE_HEADERS)
 
 
-_USER_GUIDE_PATH = Path("docs/guida-utente.md")
-
-
 @app.get("/guida", include_in_schema=False)
 async def user_guide() -> FileResponse:
-    """Serves docs/guida-utente.md as plain text so it opens inline in the
-    browser (no markdown rendering — keeps this simple), linked from the
-    navbar's help button in app/static/index.html.
+    return FileResponse("app/static/guida.html", headers=_NO_STORE_HEADERS)
 
-    The Dockerfile must COPY docs/ for this to exist inside the container (it
-    didn't, which made this a guaranteed 500 in every real deployment — B-16).
-    Answers a clean 404 if the file is missing rather than an unhandled error."""
-    if not _USER_GUIDE_PATH.is_file():
-        logger.error("user guide missing at %s (is docs/ shipped in the image?)", _USER_GUIDE_PATH)
-        raise http_error(status.HTTP_404_NOT_FOUND, "guide_unavailable", "user guide not available")
-    return FileResponse(_USER_GUIDE_PATH, media_type="text/plain; charset=utf-8")
+
+@app.get("/report-bug", include_in_schema=False)
+async def report_bug_page() -> FileResponse:
+    return FileResponse("app/static/report-bug.html", headers=_NO_STORE_HEADERS)
 
 
 app.mount("/", StaticFiles(directory="app/static", html=True), name="static")