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-codec/src/proxymanager.rs

@@ -19,12 +19,12 @@
 //! Mirrors `src/codec/src/proxymanager.h`. Stateless (NOTES.md): actual
 //! transcodes are delegated to the global task submit callback
 //! ([`crate::task`]); with no registrar, `get_or_start` reports the proxy
-//! as missing. `proxy_params_from_config` reads the oakcommon config store
+//! as missing. `proxy_params_from_config` reads the oak_core config store
 //! with the compiled-in defaults as fallback (1280x720 / divider 1 / crf 23
 //! / "mp4" / "veryfast" / audio included).
 
-use oak_common::configstore::ConfigStore;
-use oak_common::filefunctions::FileFunctions;
+use oak_core::configstore::ConfigStore;
+use oak_core::filefunctions::FileFunctions;
 use std::path::Path;
 
 /// Proxy state of a proxy file on disk.
@@ -127,13 +127,13 @@ impl ProxyManager {
 		ProxyParams::default()
 	}
 
-	/// Proxy parameters read from the oakcommon config, with the compiled-in
+	/// Proxy parameters read from the oak_core config, with the compiled-in
 	/// defaults as fallback.
 	///
 	/// # CPP-PARITY
 	/// `src/codec/src/proxymanager.h` `proxy_params_from_config` — reads
 	/// ProxyWidth/ProxyHeight/ProxyDivider/ProxyCRF/ProxyPreset/
-	/// ProxyIncludeAudio via `oakcommon_config_*`.
+	/// ProxyIncludeAudio via `oak_core_config_*`.
 	pub fn proxy_params_from_config() -> ProxyParams {
 		let mut p = ProxyParams::default();
 		p.width = config_get_int("ProxyWidth", p.width);
@@ -387,17 +387,17 @@ fn cstr_slice(a: &[u8; 32]) -> &str {
 	std::str::from_utf8(&a[..end]).unwrap_or("")
 }
 
-/// `oakcommon_config_get_int` wrapper (null group).
+/// `oak_core_config_get_int` wrapper (null group).
 fn config_get_int(key: &str, default: i32) -> i32 {
 	ConfigStore::instance().get_int(None, key, default)
 }
 
-/// `oakcommon_config_get_bool` wrapper (null group).
+/// `oak_core_config_get_bool` wrapper (null group).
 fn config_get_bool(key: &str, default: i32) -> i32 {
 	ConfigStore::instance().get_bool(None, key, default)
 }
 
-/// `oakcommon_config_get` string read; `None` when the stored value is
+/// `oak_core_config_get` string read; `None` when the stored value is
 /// empty or absent.
 fn config_get_str(key: &str) -> Option<String> {
 	match ConfigStore::instance().get(None, key) {
@@ -406,14 +406,14 @@ fn config_get_str(key: &str) -> Option<String> {
 	}
 }
 
-/// `oakcommon_filefunctions_get_unique_file_identifier` wrapper.
+/// `oak_core_filefunctions_get_unique_file_identifier` wrapper.
 fn unique_file_identifier(filename: &str) -> String {
 	FileFunctions::new()
 		.get_unique_file_identifier(filename)
 		.unwrap_or_default()
 }
 
-/// `oakcommon_filefunctions_get_application_path` read.
+/// `oak_core_filefunctions_get_application_path` read.
 fn application_path() -> String {
 	FileFunctions::new()
 		.get_application_path()