JASS location lifecycle

RemoveLocation (game/api/api_math.h) invalidates the VM-owned location reference shared by all JASS copies of that handle. jdo.c rejects access through jass_checkhandle, so GetLocationX/Y/Z return their existing null fallback and MoveLocation does nothing. Removing a null/already removed location is harmless. Memory stays VM-owned until its last reference retires; no alias can accidentally dereference a freed payload.

jstate.h carries an explicit invalid bit instead of repurposing id = 0. This is important because value-handle types such as race use zero IDs and must remain valid. JASS snapshot writing encodes invalidated handles using the existing null encoding; snapshots never serialize a zero-ID owned payload. Existing, valid owned handles still use ID-based alias deduplication. Restored removed globals become null, so they cannot be used after load.

Tests: wc3_api.remove_location_invalidates_aliases and wc3_api.removed_location_global_survives_save_as_null exercise native dispatch, aliases, idempotence, null, and a full game save/load round-trip. Changes to location serialization should update these tests and save/load documentation.