Add kOfxParamPropColourManaged for colour-managed RGB/RGBA params (#158)

[garyo]

Implements the agreed spec change from #158. Companion to #244 (the contrib/colour conversion library).

What

Adds kOfxParamPropColourManaged, a boolean parameter property a plug-in can set on an RGB or RGBA parameter to declare that the parameter's values — including its default — are in the ACES2065-1 (AP0) reference colourspace rather than an unmanaged, display-referred encoding. The values are scene-linear and not constrained to [0..1], so a colour-managed host (or any host that supports wide-gamut colours) can interpret and convert them correctly.

Plug-ins must check the set status: if the host does not implement the property, they should fall back to old-style colour values. It defaults to 0, so existing plug-ins are unaffected.

Changes

• include/ofxParam.h: the property with its @propdef metadata (bool, dim 1), plus new ParamsRGB and ParamsRGBA property sets — the colour param types were not previously modelled in the property metadata system.
• Documentation/sources/Reference/ofxParameter.rst: describes the property in the Colour Parameters section.
• release-notes.md: noted under 1.5.1.
• openfx-cpp/include/openfx/*: regenerated metadata, property sets, and typed accessors via scripts/gen-props.py.

Validation

• scripts/gen-props.py passes all checks (metadata present, every prop used in a set).
• The property resolves to bool / dimension 1 / default false consistently across the generated metadata and accessors (ParamsRGB::setColourManaged(bool) etc.).

Note: introduced: "1.5.1" to match the current in-progress version; easy to bump to 1.6 if preferred.

🤖 Generated with Claude Code

[revisionfx]

A documentation note was host should save such parameter value(s) in project file in ACES2065-1 so as we increase interoperability between apps, this stays robust. And to be clear if this property is supported, plugin is expected to create default values in ACES2065-1.

Of course hard to test right now :)

[garyo]

Thanks for the note, Pierre — added that now (both header and doc). And I note that you can test the colour-conversion lib any time; that's totally standalone, usable by any host or plug-in.