Run Lua inside grandMA3

FALLBACK: use a structured tool when one fits; they check, read back and need no Lua. Patch: gma3_patch_library, gma3_patch_import, gma3_patch_add, gma3_patch_set, gma3_patch_move, gma3_patch_stages, gma3_patch_retype, gma3_patch_type_structure, gma3_place_fixtures, gma3_layout_cells. Dialogs: gma3_dialog (never Mouse()). Groups: gma3_store_group, gma3_configure_matricks. Presets: gma3_apply_preset, gma3_store_preset. Phasers: gma3_build_phaser. Looks: gma3_set_attributes. Cues: gma3_store_cues, gma3_edit_cues, gma3_build_chase, gma3_cue_contents. Recipe cues: gma3_store_recipe_cues, then gma3_cook_recipes. Playback: gma3_configure_sequence, gma3_configure_executor, gma3_playback, gma3_goto_cue. Reads: gma3_objects, gma3_get_object, gma3_list_children, gma3_programmer; used and free pool numbers and executors: gma3_pool_usage. Many objects at once: gma3_store_group (groups), gma3_store_preset (presets, each from explicit content), gma3_store_macro (macros), gma3_edit_macro_line (edits), gma3_assign_to_executor (assignments), gma3_configure_sequence (sequences, with ranges), gma3_set_variable (variables), gma3_store_cues (sequences), gma3_store_tag (tags), gma3_delete_tag (tags), gma3_assign_tag (assignments), gma3_configure_tag (tags) take lists with per-item checks and read-back; never loop over them in Lua. Watching over time: gma3_observe_tempo (how fast running sequences (chases) advance), gma3_observe_values (programmer or DMX output values of fixtures as they change), gma3_build_chase (one cycle of the chase it built), gma3_run_macro (a macro's running line), gma3_timecode_transport (a timecode show's cursor and the sequences it fires). They sample server-side; never write a Lua waiting or polling loop (gma3_lua has a 5 s budget). Evaluate Lua 5.4 code inside the grandMA3 Lua engine and return the result(s) as JSON. The code is first compiled as an expression ('return '), then as a statement block. All grandMA3 Lua API functions are available (Cmd, ObjectList, DataPool, Root, ShowData, Patch, Programmer, SelectedSequence, GetCurrentCue, GetExecutor, GetVar/SetVar, Printf, Echo, Enums, ...). Object handles are returned as {name, class, addr, addrNative, index, childCount}; use handle:Get('Prop') to read properties, :Children(), :Count(), :Ptr(i). Examples: 'SelectedSequence().name', 'GetCurrentCue():Get("No")', 'DataPool().Sequences:Count()', 'local t={} for i,c in ipairs(ObjectList("Fixture Thru")) do t[#t+1]=c.name end return t'. Use gma3_lua_api to look up function signatures. This capability is OFF by default on the console: the operator enables it by starting the bridge with Plugin "gma3_mcp_bridge" "lua" or running Plugin "gma3_mcp_bridge" "lua on" (gma3_status shows the policy). Each request runs under the console's execution budget (default 5 s wall-clock / 20 M VM instructions, operator-configurable) and is aborted with an error when it exceeds it, so keep scripts short and prefer the structured tools (gma3_get_object, gma3_list_children, gma3_objects) for bulk reads. By default the console's own hook on the plugin thread is preserved, which means the instruction budget is NOT enforced and the deadline is only checked when the script yields or returns: a script that loops without yielding cannot be stopped (gma3_status shows lua.bounded; the result's budget.instructionHookEnforced says what applied). The operator can start the bridge with luahook=replace to enforce hard quotas. Because a script may call Cmd() or Set(), every gma3_lua request is serialised with this server's other mutations (it waits for a running workflow and blocks later ones while it runs).