Implement BotResetLastAvoidReach tracking and export

[themuffinator]

Motivation

• Mirror Quake III behavior by tracking the last avoided reachability separately from the general avoid list so it can be cleared independently.
• Ensure movement state stores per-movestate last-avoid metadata to match retail logic used by combat/navigation code.

Description

• Added fields to bot_movestate_t (lastavoidreach, lastavoidreachtime, lastavoidreachtries, lastavoidreachindex) in src/botlib/ai_move/bot_move.h to track the most-recently avoided reachability.
• Updated BotMove_RefreshAvoidReach in src/botlib/ai_move/bot_move.c to compute and cache the most-recent avoid entry and its metadata.
• Implemented BotMove_ResetLastAvoidReach (clears the cached timer and decrements tries) and wired it into BotMove_ResetAvoidReach to clear last-avoid fields when resetting all avoids.
• Exported the new helper via the interface by adding BotResetLastAvoidReach to src/q2bridge/botlib.h and src/botlib/interface/bot_interface.c so the botlib API exposes the function.

Testing

• No automated tests were executed for this change.
• Code compiled was not verified in CI as part of this change (no build/test run was requested).

---

Codex Task