server: select viable hunts with recovery income

[adrunkhuman]

Closes #182.

• Reject standalone hunts with at most three reachable spawns, while retaining small pockets inside larger circuits. Larger hunts need a meaningful replenishing core; losing a modeled waypoint ends the hunt rather than silently shrinking its patrol.
• Estimate gross coin gold/minute from loaded loot and patrol availability. Prefer income over XP when recovery supplies are low and resupply is unaffordable, after existing safety and supply-budget preferences. Keep income alternatives in the bounded route shortlist.
• Report expected income and verified coin pickups separately from sale-valued loot. Keep hunt facts separate from selection preferences for later personality work.
• Align the mainland hunt fixtures with the tracked Knight loadout and add contracts for viability, coin arithmetic, cash-pressure selection, and patrol invalidation.

Replenishment remains a bounded patrol-duty heuristic, not a guarantee of spawn timing or sustainable level 8–20 progression. This excludes resale/net-profit accounting, personality implementation, and faster adaptive difficulty escalation. Production seed funds, equipment, potion thresholds, and route-safety limits are unchanged.