feat(nws, normalizers): add NWS hourly forecast normalization and enforce canonical float rounding

- Implement full NWS hourly forecast normalizer (raw.nws.hourly.forecast.v1 → weather.forecast.v1)
- Add GeoJSON forecast types and helpers for NWS gridpoint hourly payloads
- Normalize temperatures, winds, humidity, PoP, and infer WMO condition codes from forecast text/icons
- Treat forecast IssuedAt as EffectiveAt for stable, dedupe-friendly event IDs

- Introduce project-wide float rounding at normalization finalization
  - Round all float values in canonical payloads to 2 decimal places
  - Apply consistently across pointers, slices, maps, and nested structs
  - Preserve opaque structs (e.g., time.Time) unchanged

- Add SchemaRawNWSHourlyForecastV1 and align schema matching/comments
- Clean up NWS helper organization and comments
- Update documentation to reflect numeric wire-format and normalization policies

This establishes a complete, deterministic hourly forecast pipeline for NWS
and improves JSON output stability across all canonical weather schemas.

internal/standards/doc.go

@@ -5,11 +5,19 @@
 //   - Schema identifiers and versioning conventions (see schema.go).
 //   - Canonical interpretations / cross-provider mappings that are not specific to a
 //     single upstream API (e.g., shared code tables, text heuristics, unit policy).
+//   - Wire-format conventions for canonical payloads.
 //
 // Standards are used by both sources and normalizers. Keep this package free of
 // provider-specific logic and free of dependencies on internal/sources/* or
 // internal/normalizers/* to avoid import cycles.
 //
+// Wire-format conventions
+// -----------------------
+// For readability and stability, canonical payloads (weather.* schemas) should not emit
+// noisy floating-point representations. weatherfeeder enforces this by rounding float
+// values in canonical payloads to 2 digits after the decimal point at normalization
+// finalization time.
+//
 // Provider-specific decoding helpers and quirks live in internal/providers/<provider>.
 // Normalizer implementations and canonical mapping logic live in internal/normalizers/<provider>.
 package standards