polish nav, planner UX, country pills, and dev magic link

- Nav: Zillow-style centered logo, solid blue Sign In button
- Planner: center app at 72rem, center wizard steps/header/preview
- Country pills: UK/USA labels, remove Other, show permits slider
  inline under country so the effect is transparent and adjustable
- Reset button: inline confirm (red "Sure? Reset") instead of alert
- Worker: print magic link to console when DEBUG=true for local dev

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

padelnomics/tests/test_calculator.py

@@ -1033,7 +1033,7 @@ plausible_state = st.fixed_dictionaries({
     "budgetTarget": st.integers(0, 5000000),
     "glassType": st.sampled_from(["standard", "panoramic"]),
     "lightingType": st.sampled_from(["led_standard", "led_competition", "natural"]),
-    "country": st.sampled_from(["DE", "ES", "IT", "FR", "NL", "SE", "UK", "OTHER"]),
+    "country": st.sampled_from(["DE", "ES", "IT", "FR", "NL", "SE", "UK", "US"]),
     "permitsCompliance": st.integers(0, 50000),
 })