Pursue monsters from their last visible position

[adrunkhuman]

Summary

• Pursue a monster's last visible approach position when normal chase loses it.
• Bound pursuit to five seconds and six tiles, require normal positional and creature visibility before reacquisition, and suppress abandoned targets briefly.
• Add successful-reacquisition and abandonment fixtures, telemetry contracts, and updated mainland playerbot documentation.

Verification

• docker compose -f server/compose.yaml build server - passed
• pwsh -File scripts/test-playerbot-gameplay.ps1 -Focused -TargetPursuit -SkipBuild - passed
• pwsh -File scripts/test-playerbot-gameplay.ps1 -Focused -FullNavigation -CorpseLoot -SkipBuild - passed

Notes

Broader playerbot perception and creature-memory policy remains tracked in #84.