feat(ingest): Ingest nested OTLP resourceSpans/scopeSpans exports and typed attributes (#11)

[IronLad123]

Closes #11

Summary

Adds support for standard, nested OpenTelemetry Collector / OTLP JSON exports (resourceSpans[].scopeSpans[].spans[]) to src/taintline/ingest.py, including typed OTLP attribute array decoding.

Key Changes

1. Nested Envelope Flattening:

   • Updated _parse_otlp(data) to auto-detect and flatten resourceSpans[].scopeSpans[].spans[] into normalized Span/Trace objects without modifying model.py.

2. Typed OTLP Attribute Array Decoding:

   • Added _normalize_attributes() and _unwrap_otlp_value() to decode OTLP attribute arrays containing typed value objects (stringValue, intValue, boolValue, doubleValue, arrayValue, kvlistValue, bytesValue) into flat attribute dictionaries.

3. Open-Closed Backward Compatibility:

   • Preserved existing flat span lists and Strands nested-dict parsing paths.

4. Portability Fixture & Testing:

   • Added portability fixture tests/fixtures/portability/otlp_nested_export.json.
   • Verified determinism across PYTHONHASHSEED=0 and PYTHONHASHSEED=42.
   • 58 / 58 tests passed (1.19s).
   • ruff check: 0 errors.