Implement and export BotReachabilityArea with mover and solid-area handling

[themuffinator]

Motivation

• Restore the missing movement perception export required by the parity matrix so origin-to-area resolution is consistent with HLIL/Quake logic.
• Ensure solid-area handling and mover-support (func_plat/func_bob) are resolved the same way retail code expects so navigation and goal selection can rely on accurate AAS areas.
• Provide an exported API for game code to query the reachability area for an origin/client pair.

Description

• Implement BotReachabilityArea in src/botlib/ai_move/bot_move.c with solid-area tracing and mover-aware handling and add helper functions BotMove_AreaHasReachability, BotMove_FuzzyPointReachabilityArea, BotMove_GetClientTraceBounds, and BotMove_FindMoverReachabilityArea.
• Add the declaration int BotReachabilityArea(vec3_t origin, int client); to src/botlib/ai_move/bot_move.h and update surrounding prototypes.
• Export the function through the public API by adding a wrapper BotInterface_BotReachabilityArea and wiring exportTable.BotReachabilityArea in src/botlib/interface/bot_interface.c, and declare the symbol in src/q2bridge/botlib.h.
• Use AAS_NextModelReachability/AAS data to detect mover reachability and Q2_Trace with the client bounding box to trace down through solids, matching the retail fuzzy-area lookup behaviour.

Testing

• No automated tests were executed for this change.

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Codex Task