fix(client): correct east/west region-map marker facing

[zoeyrose]

Problem

The Classic client's region-map player marker shows the opposite horizontal facing:

• When the player faces east, the marker points west.
• When the player faces west, the marker points east.
• North and south are displayed correctly.

This was observed on the circular minimap. The full region-map popup uses the same marker renderer and should be checked as well.

Reproduction

1. Start the Classic client in an area with a region map.
2. Face or move the player east and observe the directional player marker.
3. Face or move the player west and observe it again.
4. Repeat with north and south as controls.

Expected behavior

The region-map marker points in the same direction as the player for every facing.

Actual behavior

East and west are reversed, while north and south match the player.

Analysis

region_map_render_marker() rotates the shared map_marker texture in 45-degree steps from map_get_player_direction(). The current angle applies a negative sign. A clockwise/counter-clockwise convention mismatch here would explain why east and west swap while the north/south axis remains correct; confirm the complete facing-to-angle mapping before changing it.

This is distinct from #118, which improved marker contrast while preserving the existing directional behavior.

Acceptance criteria

• The marker matches the player for all eight facing directions in the circular minimap.
• The marker matches the player for all eight facing directions in the full region-map popup.
• East and west are no longer swapped, and the currently correct north/south behavior does not regress.
• The facing-to-rotation mapping has focused regression coverage where practical.
• Marker centering, clipping, scaling, contrast, and fog layering remain unchanged.

Validation

• ./atrinik build client --profile classic --test
• Visual verification of all eight facings in both region-map surfaces
• git diff --check