Add float32 and float64 field comparison tags

[leocavalcante]

Fixes #79

Summary

• Accept eqfield, neqfield, gtefield, gtfield, ltefield, and ltfield on float32 and float64.
• Generate Go ==, !=, >=, >, <=, and < checks. Same operators as integer field tags, and the same comparisons go-playground/validator v10.28.0 makes with field.Float(). No epsilon.
• Keep rejecting mixed types (float32 vs float64, float vs int) and slice or map float field comparisons.

Test plan

• go test ./internal/analyzer/... ./internal/codegenerator/ ./types/...
• make endtoendtests, including float32 and float64 inner and nested fields: unequal values, equal values, and ordering
• Reviewer: confirm generated checks use direct Go operators with no epsilon