expose complex-scripts feature (#24094)

[unclepomedev]

Objective

Fixes #24094

Text containing complex scripts that lack explicit word boundaries (CJK, Thai, Khmer, Lao, Myanmar) is segmented by parley's lightweight segmenter, which emits a data error per layout:

ICU4X data error: No segmentation model for language: ja

parley added a complex-scripts Cargo feature that switches to dictionary-based segmentation, but it was not reachable from Bevy.

Solution

• Add an opt-in complex_script_segmentation feature to bevy_text that forwards to parley/complex-scripts, propagated through bevy_internal and bevy. It is off by default because the bundled segmentation dictionary increases binary size.

This supplies the segmentation data and enables dictionary-based word segmentation; it does not change CJK line-break positions, which ICU keeps permissive by design.

Testing

• cargo build -p bevy_text -p bevy_ui -p bevy_ui_widgets, with default features and with --features complex_script_segmentation.
• cargo tree -e features -i parley confirms parley's complex-scripts feature is only enabled when complex_script_segmentation is requested (not pulled in by any default/collection feature).
• Ran a Text2d example with a Japanese string in a width-bounded box (TextBounds, LineBreak::WordBoundary) under RUST_LOG=warn:
  • default: the No segmentation model for language: ja error is logged.
  • --features complex_script_segmentation: the error is gone.
• cargo run -p ci (lints + compile + tests). One unrelated local failure: bevy_ecs ... filtered_backtrace_test, which also fails on main on my machine (an environment-dependent backtrace-symbolization test, unrelated to this PR).
• Tested on macOS (Apple Silicon).

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[unclepomedev]

The previous commit is a squash of all commits. It was also intended to re-trigger the CI that had failed due to a network error.

[Copilot]

Pull request overview

This PR adds an opt-in complex_script_segmentation Cargo feature to the bevy feature graph (via bevy_text → bevy_internal → bevy) and documents it, enabling dictionary-based segmentation for complex scripts when requested.

Changes:

• Adds complex_script_segmentation to bevy_text and forwards it to parley/complex-scripts.
• Propagates complex_script_segmentation through bevy_internal and the top-level bevy crate features.
• Documents the new feature in docs/cargo_features.md.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
docs/cargo_features.md	Documents the new complex_script_segmentation feature (but currently has a duplicated row that should be fixed).
crates/bevy_text/Cargo.toml	Adds a complex_script_segmentation feature that forwards to parley/complex-scripts.
crates/bevy_internal/Cargo.toml	Plumbs complex_script_segmentation through bevy_internal to bevy_text.
Cargo.toml	Exposes complex_script_segmentation as a top-level bevy feature via bevy_internal.

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[unclepomedev]

Removed the parley version bump since it was already merged separately.
Re-verified after resolving the merge conflict against current main: the No segmentation model for language: ja error still reproduces by default, and --features complex_script_segmentation still resolves it.
The current CI failure seems unrelated to this PR (filed as #24902)