fix: model registration modules must not be tree-shaken

[ronaldtse]

Summary

• "sideEffects": false let esbuild drop the bare import "./models/rababa/index.js" / secryst/index.js in dist/ml/index.js — those side-effect imports are the registerModel calls
• consequence: any consumer bundling with esbuild/webpack (the api-worker did) silently shipped with zero ML models registered
• declare the registration modules side-effectful with a targeted glob; tree-shaking elsewhere is unchanged

Test plan

• CI green
• consumer bundle now contains createRababaModel (verified in the api-worker rebuild)