Low: npc_movearmy() High Movement Points Edge Case

[smooge]

Priority: LOW
File: Src/moveA.c
Function: npc_movearmy()
Discovered: During Phase 6B-1 unit testing (11/12 tests pass)

Description: Function handles high movement points (≥100) with unexpected calculation logic in edge case scenario.

Reproduction Steps:

1. Create test army with 150 movement points
2. Set mock movement cost to 200 (higher than available)
3. Call npc_movearmy(11, 21)
4. Expected: Returns TRUE, movement points reduced to -50 (over-expenditure allowed)
5. Actual: Returns TRUE, movement points set to 206 (unexpected calculation)

Impact: Minor edge case behavior difference that may affect game balance in high-movement scenarios, but doesn't break core functionality.

Proposed Fix: Investigate the high movement point logic in the function to understand the intended behavior when umove ≥ 100. May be working as designed.

Original Bug ID: BUG-009