Add parity guards & diagnostics to move-state APIs

[themuffinator]

Motivation

• Bring movement-related APIs into parity with HLIL by emitting the same diagnostics when the bot library is uninitialised or move-state handles are invalid.
• Prevent callers from observing stale or uninitialised output by clearing moveresult buffers where required.
• Provide a single, reusable library-initialisation guard so callers can report the canonical HLIL message.
• Ensure avoid-reach state is reset by clearing the underlying arrays as the HLIL behaviour indicates.

Description

• Added BotLibraryEnsureInitialized and its prototype in src/botlib/interface/botlib_interface.{c,h} which emits the HLIL diagnostic "%s: bot library used before being setup\n" when the library is not initialised.
• Implemented BotMove_ResolveMoveState in src/botlib/ai_move/bot_move.c to centralise move-state handle validation and emit the HLIL parity diagnostic "%s: index %d not setup\n" on invalid handles.
• Updated movement entry points in src/botlib/ai_move/bot_move.c (BotAllocMoveState, BotResetMoveState, BotInitMoveState, BotMoveToGoal, BotMoveInDirection) to call the new initialisation guard and/or handle resolver, and to clear output where appropriate (notably BotMoveToGoal now calls BotClearMoveResult early).
• Added the required commented function headers above the modified movement functions and left BotMove_ResetAvoidReach implementation that clears avoidreach, avoidreachtimes and avoidreachtries with memset, matching HLIL behaviour (and BotResetAvoidReach in bot_goal.c also performs equivalent clears).

Testing

• No automated tests were executed for this change.
• The change compiles/committed to the branch (changes staged and committed), but no CI/build verification was run in this rollout.
• Static inspections: code paths for invalid-handle and uninitialised-library now produce the HLIL-style diagnostic messages via BotLib_Print.
• Manual runtime validation is recommended (start with calls to BotMoveToGoal/BotMoveInDirection before BotSetupLibrary and with invalid handles to observe the diagnostic output).

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Codex Task