Rebuild Home around a forest header with streak, score and water

Home now opens on a deep green header: greeting, a Today / Weekly toggle,
a seven-day streak with a leaf on every kept day, minutes held with a +
ring, plan thumbnails, the report-card letter as the score, and one bar per
commitment class (weekly view swaps in per-day bars and class rates). The
+ opens an "Add to today" sheet over the blurred day. A water tracker sits
below the header, kept on the device. The nav marks the selected tab as a
filled block and drops the side action button.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KhQh614DMeYoQEH9SoMRUw

frontend/lib/Grounded/utils/Colors.dart

@@ -127,6 +127,21 @@ const Color colorOverdueWarm = Color(0xFFF9E1D8);
 const Color colorOverdueWarmEnd = Color(0xFFFFF6EF);
 const Color colorOverdueGlow = Color(0xFFD7654B);
 
+// ── Home header ───────────────────────────────────────────────────────────────
+// The deep forest block the day sits in, with brighter bars that read on it.
+const Color colorHeaderTop = Color(0xFF203D30);
+const Color colorHeaderBottom = Color(0xFF15281F);
+const Color colorHeaderPanel = Color(0x14FFFFFF);
+const Color colorHeaderLine = Color(0x26FFFFFF);
+const Color colorHeaderMuted = Color(0x99FFFFFF);
+const Color colorHeaderSelected = Color(0xFF3D6B53);
+const Color colorBarNonNegotiable = Color(0xFFE8735A);
+const Color colorBarStandard = Color(0xFFF2C14E);
+const Color colorBarElective = Color(0xFF6FD39B);
+// Water: filled drops and the empty ones.
+const Color colorWater = Color(0xFF6E8EF0);
+const Color colorWaterEmpty = Color(0xFFDDE1DE);
+
 // ── Scene art ─────────────────────────────────────────────────────────────────
 // The painted landscapes that stand in for photography on cards. Each kind has
 // a sky (top → horizon), a sun, three ridges (far → near) and an ember accent.