Task 434: Replace Hardcoded Ship Parameters in templates.ts with KESTREL Constants

Status: DONE

Summary

Replace hardcoded mass (48000), thrust (9.8/6.37), and Isp values in templates.ts with derived values from KESTREL constants. Two locations: CALC_EPISODE_PRESETS defaults and standalone brachistochrone calculator HTML.

Rationale

• Hardcoded literals in templates.ts won't update if KESTREL constants change
• kestrel.test.ts validates constants but can't catch template drift
• Simple fix: import KESTREL and derive display-unit values