docs: Document the sbt-uni-crossproject plugin

[xerial]

What

Adds a Build Tooling reference page for sbt-uni-crossproject (merged in #623), mirroring the sbt-uni-playwright page, and links it in both duplicated sidebars in config.mts.

Covers: installation (with __UNI_VERSION__), the crossProject(...) usage and val-name → coreJVM/coreJS/coreNative derivation, the CrossType.Pure directory layout, the %%-on-sbt-2.x note, and a supported-API table — all verified against the merged source.

Validation

pnpm docs:build succeeds (no dead links).

🤖 Generated with Claude Code

[gemini-code-assist]

Code Review

This pull request adds documentation for the new sbt-uni-crossproject plugin, including updating the VitePress sidebar configuration. The review feedback focuses on improving the documentation by using the more idiomatic Test configuration object instead of the string literal "test", ensuring consistency in method naming within the API table, and documenting the .configs(...) method.

Important

The consumer version of Gemini Code Assist on GitHub is being sunset. Starting June 18, 2026, new organization installations will be blocked, and all code review activity will officially cease on July 17, 2026.
For more details on the timeline and next steps, please review the Help Documentation.

[gemini-code-assist]

In sbt, it is more idiomatic and common to use the Test configuration object (e.g., core % Test) rather than the string literal "test" (e.g., core % "test"). Since the scripted tests for this plugin also use core % Test, updating this example to use Test improves consistency and follows standard sbt practices.

Suggested change

	.dependsOn(core, core % "test")
	.dependsOn(core, core % Test)

[gemini-code-assist]

The methods .jvmSettings, .jsSettings, .nativeSettings, .jvmConfigure, .jsConfigure, and .nativeConfigure all accept arguments (e.g., settings definitions or project transformers). Adding parentheses/parameter placeholders (like (...)) to these method names in the table makes them consistent with other methods like .settings(...) and .configure(...).

Suggested change

	| `.jvmSettings` / `.jsSettings` / `.nativeSettings`| Settings applied to one platform only |
	| `.configure(...)` / `.jvmConfigure` / `.jsConfigure` / `.nativeConfigure` | Apply `Project => Project` transforms |
	| .jvmSettings(...) / .jsSettings(...) / .nativeSettings(...) | Settings applied to one platform only |
	| .configure(...) / .jvmConfigure(...) / .jsConfigure(...) / .nativeConfigure(...) | Apply Project => Project transforms |

[gemini-code-assist]

The CrossProject class also exposes a public .configs(...) method (defined on line 55 of CrossProject.scala) to add configurations to all platform projects. It would be beneficial to document this method in the API table to ensure completeness.

Suggested change

	| `.enablePlugins(...)` / `.disablePlugins(...)` | Enable/disable sbt plugins on every platform project |
	| .enablePlugins(...) / .disablePlugins(...) | Enable/disable sbt plugins on every platform project |
	| .configs(...) | Add configurations to every platform project |

[gemini-code-assist]

Using the Test configuration object is more idiomatic in sbt than the string literal "test". Updating this row to use Test aligns with standard sbt practices.

Suggested change

	| `.dependsOn(other, other % "test")` | Depend on another cross-project, optionally scoped to a config|
	| .dependsOn(other, other % Test) | Depend on another cross-project, optionally scoped to a config |