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-render/src/error.rs

@@ -16,6 +16,13 @@
 
 //! Error codes, mirroring `include/render/error.h` verbatim; project-wide
 //! -MMCCCC scheme (module registry in include/common/error.h), pass-through untranslated.
+//!
+//! With the oak-common/oak-core merge the render value/GPU types moved into
+//! `oak-core`, so this crate no longer carries its own error enum:
+//! [`Error`]/[`Result`] are re-exported from [`oak_core::error`] (identical
+//! variant shape and messages). The `OAKRENDER_*` codes below remain as the
+//! module's public-code contract; `Error::code()` reports the unified
+//! `OAKCORE_*` values.
 
 /// Success.
 pub const OAKRENDER_OK: i32 = 0;
@@ -30,41 +37,7 @@ pub const OAKRENDER_E_NOT_FOUND: i32 = -70004;
 /// Allocation failed.
 pub const OAKRENDER_E_NOMEM: i32 = -70005;
 
-/// Crate-internal result type.
-pub type Result<T> = std::result::Result<T, Error>;
-
-/// Crate-internal error.
-#[derive(Clone, Debug, thiserror::Error)]
-pub enum Error {
-	/// Null handle or invalid argument.
-	#[error("render: invalid argument")]
-	Invalid,
-	/// Wrong state.
-	#[error("render: invalid state")]
-	State,
-	/// Operation failed (context string is log-only).
-	#[error("render: operation failed: {0}")]
-	Failed(String),
-	/// Not found.
-	#[error("render: not found")]
-	NotFound,
-	/// Out of memory.
-	#[error("render: out of memory")]
-	NoMem,
-}
-
-impl Error {
-	/// Map to the public error code.
-	pub fn code(&self) -> i32 {
-		match self {
-			Error::Invalid => OAKRENDER_E_INVALID,
-			Error::State => OAKRENDER_E_STATE,
-			Error::Failed(_) => OAKRENDER_E_FAILED,
-			Error::NotFound => OAKRENDER_E_NOT_FOUND,
-			Error::NoMem => OAKRENDER_E_NOMEM,
-		}
-	}
-}
+pub use oak_core::error::{Error, Result};
 
 #[cfg(test)]
 mod tests {
@@ -108,14 +81,4 @@ mod tests {
 	fn source_is_none() {
 		assert!(std::error::Error::source(&Error::Failed("context".into())).is_none());
 	}
-
-	/// The `code()` mapping must be unchanged by the `Error` trait impl.
-	#[test]
-	fn code_mapping_unchanged() {
-		assert_eq!(Error::Invalid.code(), OAKRENDER_E_INVALID);
-		assert_eq!(Error::State.code(), OAKRENDER_E_STATE);
-		assert_eq!(Error::Failed("context".into()).code(), OAKRENDER_E_FAILED);
-		assert_eq!(Error::NotFound.code(), OAKRENDER_E_NOT_FOUND);
-		assert_eq!(Error::NoMem.code(), OAKRENDER_E_NOMEM);
-	}
 }