refactor: remove QR code module (frontend handles it)

QR generation is a pure client-side operation — no need for backend.
Removes qr/ package, tests, qrcode[pil] dependency, and router registration.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: ImTotem

pyproject.toml

@@ -17,7 +17,6 @@ dependencies = [
 
     "resend>=2.0.0",
     "authzed>=1.0.0",
-    "qrcode[pil]>=8.0",
 ]
 
 [project.optional-dependencies]

src/bcsd_api/main.py

@@ -10,7 +10,6 @@
 from .dependencies import get_authz, get_settings, get_sheets
 from .exception import register_handlers
 from .member.router import router as member_router
-from .qr.router import router as qr_router
 from .redirect import router as redirect_router
 from .shorten.router import router as shorten_router
 from .track import router as track_router
@@ -65,7 +64,6 @@ def create_app() -> FastAPI:
     app.include_router(member_router)
     app.include_router(track_router)
     app.include_router(shorten_router)
-    app.include_router(qr_router)
     app.include_router(redirect_router)
     return app