Improve navigation between main app, conditions, and dashboard

- Main app: split tagline into attribution + Station/Dashboard nav pills (always visible, styled with border/hover)
- Conditions page: add Dashboard → link and ← App back-link in header
- Dashboard: add Conditions link, rename App → ← Weather in header nav

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

app/public/style.css

@@ -109,6 +109,26 @@ a:hover { text-decoration: underline; }
 }
 .tagline-link:hover { opacity: 1; text-decoration: underline; }
 
+.station-links {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+}
+.station-link {
+  font-size: 0.78rem;
+  font-weight: 600;
+  letter-spacing: 0.06em;
+  text-transform: uppercase;
+  color: var(--card-sub);
+  text-decoration: none;
+  opacity: .85;
+  padding: 0.2rem 0.5rem;
+  border: 1px solid var(--border);
+  border-radius: 5px;
+  transition: opacity .15s, background .15s;
+}
+.station-link:hover { opacity: 1; background: var(--card-bg-soft); }
+
 .settings-nav-links {
   display: flex;
   gap: 0.6rem;