feat: add configurable CSS asset names

[mohamedmansour]

Summary

• Add Link-mode CSS file name templating with [name], [hash], and [ext] tokens, defaulting to [name].[ext].
• Add optional CSS public base support so generated stylesheet hrefs can target CDN/public asset roots while local CSS files still write to the build output.
• Move CSS link href resolution into webui-parser, share cached resolution across parser/build consumers, and keep parser construction ergonomic with ParserOptions.
• Expose the options through Rust, CLI, Node native bindings, the TypeScript package API, and docs.

Documentation

• Updated DESIGN.md, CLI docs, Rust/Node integration docs, docs/ai.md, crate READMEs, and package README.

Validation

• pnpm --filter @microsoft/webui build
• cargo xtask check
• Security review: no high-confidence vulnerabilities found

Fixes #310
Fixes #311

[Copilot]

Pull request overview

This PR adds configurable Link-mode CSS asset naming (including content-hash support) and an optional public base prefix for emitted stylesheet hrefs, threading the configuration across the Rust core, CLI, Node bindings/TS API, and documentation.

Changes:

• Introduces Link-mode CSS filename templating ([name], [hash], [ext]) and css_public_base for CDN/public URL prefixing.
• Moves CSS link href/filename resolution into webui-parser (CssLinkOptions / ParserOptions) and re-plumbs parser/plugin construction to use options at creation time.
• Exposes the new options via Rust BuildOptions, CLI flags, Node native bindings, the TS package API, and updates docs/spec.

Reviewed changes

Copilot reviewed 31 out of 32 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
packages/webui/src/index.ts	Adds JS API options and CLI fallback flags for CSS template/public base.
packages/webui/README.md	Documents new JS build options.
examples/demo/server/src/shell.rs	Updates example to use BuildOptions::default() struct update pattern.
examples/app/commerce/server/src/frontend.rs	Updates example construction to use defaults + overrides.
docs/guide/integrations/rust.md	Documents new Rust build options.
docs/guide/integrations/node.md	Documents new Node build options.
docs/guide/cli/index.md	Documents new CLI flags + guidance for hashing/CDN base.
docs/ai.md	Updates AI-facing CLI reference for new flags.
DESIGN.md	Updates spec for Link-mode CSS href behavior and parser options construction.
crates/webui/src/lib.rs	Adds new build options defaults, integrates ParserOptions, resolves CSS href/filenames, adds tests.
crates/webui/src/error.rs	Adds InvalidBuildOptions error variant.
crates/webui/README.md	Documents new Rust build options and recommended CDN/hash usage.
crates/webui/examples/streaming_resource_bench.rs	Updates to new BuildOptions::default() pattern.
crates/webui/examples/streaming_e2e_ttfb_bench.rs	Updates to new BuildOptions::default() pattern.
crates/webui/benches/streaming_bench.rs	Updates to new BuildOptions::default() pattern.
crates/webui/benches/contact_book_bench.rs	Updates to new BuildOptions::default() pattern.
crates/webui-wasm/src/lib.rs	Switches to HtmlParser::with_options(...) API.
crates/webui-press/src/build.rs	Updates builder construction to use defaults + overrides.
crates/webui-parser/src/plugin/webui.rs	Moves plugin configuration to configure(&ParserOptions).
crates/webui-parser/src/plugin/mod.rs	Adds ParserPlugin::configure hook.
crates/webui-parser/src/plugin/fast_v3.rs	Uses processed templates for consistent CSS links; adds css-link-aware generation helper.
crates/webui-parser/src/plugin/fast_v2.rs	Same as fast_v3 changes for FAST v2.
crates/webui-parser/src/lib.rs	Introduces ParserOptions and new parser constructors; updates template processing to use options.
crates/webui-parser/src/css_link.rs	New module implementing template + public-base resolution and caching.
crates/webui-parser/Cargo.toml	Adds sha2 dependency for content hashing.
crates/webui-parser/benches/parser_bench.rs	Updates bench to new parser construction API.
crates/webui-node/src/lib.rs	Exposes new options through N-API bindings.
crates/webui-cli/src/commands/serve.rs	Updates CLI tests/config to include new build options fields.
crates/webui-cli/src/commands/common.rs	Adds CLI flags, wiring into BuildOptions, and a unit test.
crates/webui-cli/src/commands/build.rs	Updates CLI build command wiring/tests to include new fields.
crates/webui-cli/README.md	Documents new CLI flags and examples.
Cargo.lock	Bumps workspace crate versions and adds sha2 to webui-parser deps.