feat(engine): clip move, clip effect_input, mandatory static FFmpeg

- oakengine_sequence_move_clip implemented for real (oaktimeline
  TrackMoveBlockCommand; fixes the graph-ownership/gap-anchor/ripple
  trim bugs the stub was hiding); same-track via the frozen C ABI,
  cross-track supported by the module command
- oaknode clip blocks now declare a tex_in texture input and set
  effect_input to it, so timeline clips can host effect chains; facade
  test covers effect insert/remove on a real clip
- oakffmpeg-link: FFMPEG_DIR is now mandatory with a clear panic (a
  Homebrew upgrade left the system ffmpeg .pc pointing at a deleted
  dav1d Cellar path, breaking links); reads a git-ignored workspace
  .env for IDEs that cannot inject env vars (RustRover); links the C++
  stdlib for C++ codec libs (svt-av1)
- oakengine re-exports oaknode so tests share one crate instance;
  it_node uses the direct instance's value type where it calls the
  module FFI (the --workspace dev-dependency feature split builds
  oaknode twice)

crates/oaknode/src/nodes/blur.rs

@@ -423,9 +423,21 @@ impl BlurFilterNode {
 	/// box/gaussian, `directional_degrees_in` only for directional, and
 	/// `radial_center_in` only for radial.
 	fn update_inputs(core: &mut NodeCore, method: i64) {
-		set_hidden(core, HORIZ_INPUT, !(method == Method::Box as i64 || method == Method::Gaussian as i64));
-		set_hidden(core, VERT_INPUT, !(method == Method::Box as i64 || method == Method::Gaussian as i64));
-		set_hidden(core, DIRECTIONAL_DEGREES_INPUT, method != Method::Directional as i64);
+		set_hidden(
+			core,
+			HORIZ_INPUT,
+			!(method == Method::Box as i64 || method == Method::Gaussian as i64),
+		);
+		set_hidden(
+			core,
+			VERT_INPUT,
+			!(method == Method::Box as i64 || method == Method::Gaussian as i64),
+		);
+		set_hidden(
+			core,
+			DIRECTIONAL_DEGREES_INPUT,
+			method != Method::Directional as i64,
+		);
 		set_hidden(core, RADIAL_CENTER_INPUT, method != Method::Radial as i64);
 	}
 }