New expedition_autocamp.go: pure decideAutopilotCamp + pitchAutopilotCamp
+ dwell-window lifecycle. Wired into tryAutoRun so the background ticker
pitches a rest camp on low HP and a base-camp waypoint on region-boss
clear; auto-pitched camps last minAutoCampDwell (4h) before the next tick
breaks them and walks. CampState.AutoPitched separates auto- vs player-
pitched camp lifetimes so a player !camp stays sticky.
Day-rollover semantics unchanged — still UTC-anchored; D2-b moves
day++/burn/threat-drift onto the camp-pitch event.
