Keep chord label rotate support consistent across states

Copilot pointed out that series-level emphasis, blur, and select label options still used the generic label type after chord labels gained radial rotation. Aligning those state label types with ChordNodeLabelOption keeps the API surface consistent, and a numeric rotation test protects the degree-to-radian path touched by the implementation.

Constraint: Chord node labels now support both numeric and radial rotation.

Rejected: Leave state label typing generic | it keeps rotate: 'radial' rejected in valid chord state options.

Confidence: high

Scope-risk: narrow

Tested: npx jest --config test/ut/jest.config.cjs --runTestsByPath test/ut/spec/series/chord.test.ts --coverage=false

Tested: npm run checktype

Tested: npx eslint --no-cache src/chart/chord/ChordSeries.ts test/ut/spec/series/chord.test.ts

Tested: npx tsc -p test/ut/tsconfig.json --noEmit --moduleResolution node --skipLibCheck

Tested: npm test -- --runInBand --coverage=false