Parse parameterized data types and combined multipliers in CSS value syntax

[Copilot]

Three CSS value syntax patterns were unparseable and skipped in tests: <boolean-expr[ <if-test> ]>, <number>{2}?, and <custom-arg>+#?.

Parser changes (value-syntax-parser.ts)

• Parameterized data types: When [ appears inside <>, peek ahead to distinguish numeric ranges ([1, 1000] — first token is text) from type constraints ([ <if-test> ] — first token is <). Constraints are folded into the data type name via depth-tracked bracket matching.

• ? after existing range multiplier: Instead of throwing "multiple multipliers on same node", ? now sets the range minimum to 0. This handles {2}? → [0, 2] and +#? → [0, ∞] with list: true.

// Previously threw errors, now parses correctly:
parseValueSyntax(`<boolean-expr[ <if-test> ]>`)  // → dataType('boolean-expr[ <if-test> ]')
parseValueSyntax(`<name>{2}?`)                    // → dataType('name', undefined, { range: [0, 2] })
parseValueSyntax(`<name>+#?`)                     // → dataType('name', undefined, { range: [0, ∞], list: true })

Test changes (css-value-syntax.spec.ts)

• Removed knownProblemticValuespacesCases skip list — all three cases now run in the spec-driven sanity suite
• Added targeted unit tests for parameterized types and combined multipliers

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