Buy justified equipment upgrades from Thais NPCs

[adrunkhuman]

Summary

• Turn Thais equipment-offer evidence into a deterministic purchase goal for readiness repairs, hunt unlocks, and strict Pareto upgrades.
• Preserve supply and recovery reserves, preflight displaced-item storage, and verify normal shop, money, item, and equipment changes before completing the goal.
• Reconstruct interrupted purchases from carried equipment and bound transaction, container, displacement, and equip retries.
• Document live equipment telemetry and the focused equipment-purchase fixture coverage.

Verification

• pwsh -File scripts/test-playerbot-gameplay.ps1 -Focused -EquipmentPurchases -SkipBuild - passed purchase, clean restart, carried resume, storage rejection, and forced transaction rejection scenarios

Closes #87.