feat: add cssPeek.peekVariables toggle (#143)

[pranaygp]

Summary

Adds a new cssPeek.peekVariables setting (boolean, default true) that lets users hide preprocessor variable definitions from peek / go-to-definition results.

• New setting declared in package.json under contributes.configuration.
• Settings interface and default settings in server/src/server.ts extended.
• Setting plumbed through connection.onDefinition and connection.onWorkspaceSymbol via getDocumentSettings / connection.workspace.getConfiguration.
• findSymbols accepts an { peekVariables?: boolean } options bag (default true) and skips SymbolKind.Variable entries when off. findDefinition forwards the option.

Closes #143

Findings about current variable behavior

I verified what vscode-css-languageservice returns from findDocumentSymbols:

Source	Symbols produced for variable definitions
SCSS $primary: red;	SymbolKind.Variable with name $primary
LESS @primary: red;	SymbolKind.Variable with name @primary
CSS :root { --primary: red; }	Not emitted as a symbol (only the :root selector is)

In practice, with the current selector regex in findSymbols, preprocessor variables are not surfaced today because the class/id/tag patterns require the name to begin with ., #, or a word-boundary on the bare identifier — $primary / @primary never match. I confirmed this with a probe against findSymbols directly.

So this PR is mostly defensive: it adds the setting and the filter so that

1. if the language service ever changes its name encoding (e.g. drops the leading $/@), or
2. someone broadens the selector regex (e.g. to support CSS custom properties via --foo),
   variables will be filtered correctly when cssPeek.peekVariables=false.

Test plan

• yarn build — passes with zero TS errors
• yarn test — 26 tests pass (3 new assertions for the toggle: on, default-on, off, plus a regression check that non-variable symbols are unaffected)
• yarn lint — clean
• yarn prettier — clean on changed files

The new tests inject a synthetic SymbolKind.Variable into the cached symbol map (whose name would normally match a class regex) to exercise the filter in isolation from the language service's name encoding.

[Copilot]

Pull request overview

Adds a cssPeek.peekVariables setting (default true) that allows users to filter out preprocessor variable definitions (SymbolKind.Variable) from peek/go-to-definition and workspace symbol results, addressing issue #143.

Changes:

• Declares the new cssPeek.peekVariables boolean configuration in package.json and extends the Settings interface/defaults in the server.
• Plumbs the setting through connection.onDefinition and connection.onWorkspaceSymbol (the latter is now async to fetch configuration).
• Extends findSymbols/findDefinition with an options bag that skips SymbolKind.Variable entries when peekVariables is false.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
package.json	Adds the new cssPeek.peekVariables contribution config.
server/src/server.ts	Extends Settings and forwards the option to findDefinition/findSymbols; makes onWorkspaceSymbol async to read config.
server/src/core/findDefinition.ts	Adds options.peekVariables (default true) and skips SymbolKind.Variable symbols when off.
tests/src/findDefinition.test.ts	Adds tests for the new toggle and a regression check for non-variable symbols.

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