feat: orientation model, password confirm, frontend build

- Collapse orientation to landscape/portrait (ribbon left = portrait standard)
- Add OrientationPicker component and wire settings sheet in HomeView
- Add password confirmation field to registration form (RepeatedType)
- Build frontend SPA to public/build/

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

src/config.h

@@ -15,13 +15,13 @@
 #define RESET_HOLD_MS  5000
 
 // ── EPD color nibbles ────────────────────────────────────────────────────────
-#define COLOR_BLACK  0x0
-#define COLOR_WHITE  0x1
-#define COLOR_GREEN  0x2
-#define COLOR_BLUE   0x3
-#define COLOR_RED    0x4
-#define COLOR_YELLOW 0x5
-#define COLOR_ORANGE 0x6
+// Verified on Waveshare 7.3" hardware. Same map on 13.3" Spectra 6.
+#define COLOR_BLACK   0x0
+#define COLOR_WHITE   0x1
+#define COLOR_YELLOW  0x2
+#define COLOR_RED     0x3
+#define COLOR_BLUE    0x5
+#define COLOR_GREEN   0x6
 
 // ── NVS ──────────────────────────────────────────────────────────────────────
 #define NVS_NAMESPACE  "pf"