docs(plan): Java conformance harness implementation plan

Three slices to land Java at TS-reference parity:
- Slice 1: 5 loader validation passes (subtype rules, dataGrid sort,
  filterable, origin paths, attr-schema) + wire into MetaDataLoader
- Slice 2: conformance harness (FixtureDiscovery, lint + conformance
  theories, empirical ledger, ConformanceAdapter)
- Slice 3: capability script execution (Result, Navigator, CapabilityBinding)

Two-oracle strategy: TypeScript reference + the proven C# port at
csharp/MetaObjects.Conformance.Tests/. Slice 0 pre-flight verifies
the existing Java CanonicalJsonSerializer is genuinely byte-identical
to the TS oracle on at least one fixture before slicing in.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: dmealing