core: merge oak-common into oak-core

oak-common is gone; its modules (configstore, xmlutils, ocioutils,
oiioutils, colormath, colortransform, videoparams, ffmpegutils, ...)
now live in oak-core alongside the value types. The render value/GPU
types moved too: backend (wgpu context + DisplayRenderer), color
(ColorProcessor over ocio-rs), texture, frame, and the commonutil
config helpers.

Fix-ups to make the merged tree build and pass tests:

- oak-core Cargo.toml: wgpu back to 25 (the moved backend code is
  written against that API generation); add the toml/quick-xml/image
  deps oak-common carried.
- lib.rs: drop the duplicate 'pub mod error;'.
- error.rs: unified OAKCORE_* codes; restore Error::new() and
  From<OcioError> from oak-common's error type.
- backend.rs/color.rs: oak_core::/oak_render:: self-references
  rewritten to crate::; the shaderfx-dependent GPU effect test moved
  to oak-render's shaderfx tests (shaderfx depends on oak-node and
  cannot live in oak-core).
- oak-render's error module re-exports oak_core::error::{Error,
  Result}; the OAKRENDER_* codes stay as the public-code contract.
- oak-node jobs.rs: ColorProcessor imported from oak_core::color.
- Integration tests repointed at oak_core::{texture, frame, backend,
  color, colormath}.
- the display-ICC regression test treats an empty OAK_DISPLAY_ICC as
  unset, matching displayicc::env_override_icc.

crates/oak-timeline/src/lib.rs

@@ -22,7 +22,7 @@
 //!
 //! ## Single-lib unification
 //!
-//! The C ABI export layer (`ffi.rs`) and the oaknode/oakundo/oakcommon
+//! The C ABI export layer (`ffi.rs`) and the oaknode/oakundo/oak_core
 //! bridge (`bridge/`) were deleted in the single-lib unification: undo
 //! commands are now `oak_undo::undocommand::UndoCommand` values (the
 //! crate's command structs implement `undocommon::Command` and are boxed

crates/oak-timeline/src/undogeneral.rs

@@ -237,7 +237,7 @@ impl TimelineAddTrackCommand {
 	/// New signature (single-lib): `pub fn new(timeline: NodeRef) -> TimelineAddTrackCommand`
 	pub fn new(timeline: NodeRef) -> Self {
 		// NOTE: the C++ reads the `AutoMergeTracks` config via
-		// `oakcommon_config_get_bool`; the module exposes no config
+		// `oak_core_config_get_bool`; the module exposes no config
 		// getter, so the default is hardcoded to `false`.
 		Self::with_automerge(timeline, false)
 	}
@@ -1179,7 +1179,7 @@ impl TimelineAddDefaultTransitionCommand {
 	fn add_transition(&mut self, c: &NodeRef, mode: CreateTransitionMode) {
 		let _ = (c, mode);
 		// NOTE: the C++ builds one child command per transition: it looks up the
-		// default transition id in the config (`oakcommon_config_get`), creates
+		// default transition id in the config (`oak_core_config_get`), creates
 		// the node (`oaknode_factory_create_from_id`), clips the neighbours'
 		// lengths (`BlockResizeCommand`/`BlockResizeWithMediaInCommand`), adds the
 		// node and connects it; the default-transition config key has no Rust