refactor: typing for pillar scores

[huang-benny]

Replaced generic Record<string, number> with a strongly typed PillarScores interface to improve type safety and code clarity.

Changes

• Created PillarScores interface with explicit properties for MAINTENANCE, QUALITY, and POPULARITY
• Applied Readonly to the public API (ScoreResult.pillarScores) while keeping internal operations mutable
• Added helper methods (updateSignalScore, updatePillarScore) directly into calculateSignalScores
• Simplified normalizePillarScores to normalize all pillars in a single function
• Refactored getSignalWeights to use Object.fromEntries and map
• Simplified calculateTotalScore by removing unnecessary checks
• Moved ScoreResult interface from analyzer.ts to types.ts

There are no changes to the CLI input or output.

[kaizencc]

nice. no additional hardcoding happens in this refactor, you are just pulling out the pillars into an enum so they can be easily referenced elsewhere