add dev_config to centralize hardcoded stuff into one place.

lib/dev_config.dart

@@ -0,0 +1,25 @@
+// lib/dev_config.dart
+/// Developer/build-time configuration for global/non-user-tunable constants.
+const int kWorldMinZoom = 1;
+const int kWorldMaxZoom = 4;
+
+// Example: Default tile storage estimate (KB per tile), for size estimates
+const double kTileEstimateKb = 25.0;
+
+// Direction cone for map view
+const double kDirectionConeHalfAngle = 15.0; // degrees
+const double kDirectionConeBaseLength = 0.0012; // multiplier
+
+// Marker/camera interaction
+const Duration kMarkerTapTimeout = Duration(milliseconds: 250);
+const Duration kDebounceCameraRefresh = Duration(milliseconds: 500);
+const Duration kDebounceTileLayerUpdate = Duration(milliseconds: 50);
+
+// Tile/Network fetch retry parameters (for tunable dev backoff)
+const int kTileFetchMaxAttempts = 3;
+const int kTileFetchInitialDelayMs = 4000;
+const int kTileFetchJitter1Ms = 1000;
+const int kTileFetchSecondDelayMs = 15000;
+const int kTileFetchJitter2Ms = 4000;
+const int kTileFetchThirdDelayMs = 60000;
+const int kTileFetchJitter3Ms = 5000;