fix(extract): emit Java generic parent relationships

[oleksii-tumanov]

Summary

• emit inherits and implements edges for parameterized Java parents
• emit generic_arg references for parent type arguments and cover class and interface cases

Fixes #1510

Result

Label-normalized relevant edges from the final patch:

[
  {
    "source": "Service",
    "target": "Base",
    "relation": "inherits",
    "confidence": "EXTRACTED"
  },
  {
    "source": "Service",
    "target": "Dependency",
    "relation": "references",
    "confidence": "EXTRACTED",
    "context": "generic_arg"
  },
  {
    "source": "Service",
    "target": "Handler",
    "relation": "implements",
    "confidence": "EXTRACTED"
  },
  {
    "source": "Service",
    "target": "Event",
    "relation": "references",
    "confidence": "EXTRACTED",
    "context": "generic_arg"
  }
]

Testing

• uv run --frozen pytest tests/test_languages.py -q -k java_generic_parents (1 passed)
• uv run --frozen pytest tests/ -q --tb=short (2442 passed, 28 skipped)
• uv run --frozen ruff check graphify/extract.py tests/test_languages.py (passed)

[safishamsi]

Thanks @oleksii-tumanov — confirmed the bug (generic parents are generic_type nodes, so the inherits/implements edge was dropped) and the fix (unwrap to the base type, type args as generic_arg). Verified edges target the base, never the Bar<...> wrapper. Landed on v8 in 1f3f1c1 with your authorship. One pre-existing limitation noted in the commit (a bare type parameter T still gets a generic_arg ref — the extractor has no type-param tracking anywhere; worth a separate follow-up, not introduced here). Closing as merged-by-port.