Fix SDK query builder contract for 0.2.1

[singaraiona]

What changed

• implement the documented RayforceSDK.col() runtime method
• generate Rayforce v2 quoted column symbols and use the v2 == / != comparison operators
• validate query-builder column names and expression arguments before rendering Rayfall
• make the browser query demo execute the same fluent API it displays
• bump the package and CDN examples to 0.2.1
• add PR CI that builds the WASM package and runs API-contract checks before merge

Root cause

The 0.2.0 TypeScript declarations and README documented rf.col(), but RayforceSDK did not implement it. The remaining expression builder also retained v1 syntax: backtick column references plus = and <> operators. The browser demo hid the problem by showing fluent query code while executing Array.filter() instead.

Release safeguards

The new contract test compares:

• JavaScript module exports against TypeScript declarations
• all 24 declared classes and their public runtime members in both directions
• documented rf.*, table.*, vec.*, col.*, result, and row usage against live objects
• every documented comparison and aggregation builder through real Rayforce v2 queries

These checks run in PR CI, the Pages build, and prepublishOnly, so a mismatch blocks publication.

Validation

• clean Emscripten 6.0.6 build from Rayforce v2.5.13
• runtime smoke tests and all README fluent query examples
• TypeScript/runtime/module-export contract audit
• exact npm publish --dry-run lifecycle
• installed rayforce-wasm-0.2.1.tgz import and rf.col() query
• strict TypeScript NodeNext consumer compile
• headless Chrome query demo with the expected two filtered rows
• workflow YAML validation

The npm tarball contains 10 files and is 672.0 kB compressed.