feat(examples): support category: and example: tags in sidebar filter

[kpal81xd]

Summary

The examples-browser sidebar filter previously did fuzzy regex matching only. It now also understands category:<name> and example:<name> tags, layered on top of the existing free-text search.

• category:<name> — exact, case-insensitive match on a category's kebab name (e.g. category:animation, category:gaussian-splatting)
• example:<name> — exact, case-insensitive match on an example's kebab name (e.g. example:blend-trees-1d)
• bare words — unchanged fuzzy behavior (whitespace → .*), matching either the category or example name
• combining — multiple tags of the same kind union (OR); tags of different kinds and free text combine (AND)

The placeholder now advertises the syntax: Filter, category:, example:.

Behavior

Filter	Result
gaussian splatting	fuzzy search (unchanged)
category:animation	exactly the animation category
example:gltf	exactly the gltf example, any category
category:animation example:blend-trees-1d	that one example
category:loaders category:animation	both categories (OR)
category:anim	no match — exact, not partial

Implementation

Single file: examples/src/app/components/Sidebar.mjs. Added a parseFilter tokenizer that separates category:/example: tags from free-text terms; filterCategories evaluates each (category, example) pair against the parsed constraints.

Testing

• npm run -s lint — clean
• npm run -s type:check:app — clean
• Standalone logic test across all cases in the table above produced the expected output.