Expand Ambassador into a chase-worthy encounter

[aebrer]

Summary

The Ambassador is a rare, passive Poolrooms entity introduced in PR 75. It currently flees from the player when observed and does nothing else. While this behavior is functional as a first-pass framework entity, it wastes the potential of an interesting non-hostile encounter. Players have no reason to chase or interact with it.

Current Behavior

• Spawns rarely in Level 1 (weight 0.25, threat level 0)
• Marked correctly as hostile = false and blocks_movement = false
• Uses AmbassadorBehavior which moves away from the player when within 18-tile sense range
• Auto-explore correctly ignores it
• Drops nothing, grants nothing, and has no interaction on contact

Proposed Behavior

The Ambassador should become a chase-worthy encounter that rewards players for successfully cornering or observing it. Possible directions (not all required):

• Rare drop: Catching the Ambassador (moving adjacent to it after it has fled) drops a unique item — e.g., "Ambassador's Calling Card" (lore item + small MIND buff), or a key/compass that reveals a secret route.
• Lore unlock: Examining the Ambassador at close range grants a unique clearance-level lore entry that cannot be obtained any other way.
• Secret level trigger: If the player manages to follow the Ambassador for N turns without it escaping, it leads to a secret sub-level or shortcut.
• Sanity interaction: Observing the Ambassador from a distance slowly restores sanity (its elusiveness is calming), but getting too close causes a spike of fear/damage (it doesn't want to be caught).

Acceptance Criteria

• Ambassador has at least one meaningful reward or interaction that justifies chasing it
• The reward/interaction is documented in EntityRegistry lore/clearance info
• Auto-explore continues to ignore the Ambassador (it remains non-hostile)
• The behavior change does not break existing AmbassadorBehavior flee logic

Context

• Introduced in PR 75 (Level 1: The Poolrooms)
• Playtest follow-up comment: Design and implement Level 1: The Poolrooms #75 (comment)

Technical Notes

• scripts/ai/behaviors/ambassador_behavior.gd — behavior class
• scripts/autoload/entity_registry.gd — entity info and lore
• scripts/world/entity_renderer.gd — visual config
• scripts/resources/level_01_config.gd — spawn table entry

[aebrer]

I like the idea of adding another light-fixture type to lvl 1, a red emergency light that doesn't flicker but does maybe pulse slowly and stably.

Then we can add a rule that ambassadors under red light become hostile or something? Could be a good mechanic, just spitballing here.

[aebrer]

I like the ambassadors being mostly non-hostile and having special lore when examined with high enough clearance. I like the idea that if clearance is high enough, we can enable spawning of an alternative exit to a secret level (you read it in the lore after all, so now you know it exists). In the long term game design, this also fits... what are they the ambassadors of? The King in Yellow of course.