Add a toggleable tile yield overlay

[ekininceleme]

Players currently need to inspect tiles individually to compare potential production when choosing colony sites. This adds an optional map-wide overlay of goods icons and amounts, toggled through View → Display Tile Yields or Ctrl+Y in both the game and map editor.

The overlay shows alternative potential outputs for a regular colonist using the tile's current resources and improvements. It uses the existing production calculation, excludes specialist/player/colony bonuses, and leaves unexplored tiles blank. Labels scale with map zoom and use translucent backgrounds for readability. The display option defaults to off, is available in Preferences, and supports older saved client options.

Validation

• Built with Apache Ant 1.10.15 and Java 21 (Java 11 source/target).
• Full JUnit suite: 442 tests passed.
• New tests cover unexplored tiles, rendering bounds at 0.5×/1×/2× scale, preservation of the graphics context, and preference migration/persistence.
• Manually checked the overlay on a loaded save on macOS, including enabling and disabling it with Ctrl+Y.