feat: experimental finder APIs and TRAPI constraint fix

[SkyeAv]

Adds a developer-friendly experimental API layer for common Translator finder workflows, plus a TRAPI attribute-constraint fix.

Experimental APIs

• Adds TCT.experimental with wrappers for pathfinder(...), neighborhood_finder(...), get_translator_resources(...), and clear_translator_resource_cache().
• Resolves labels and CURIEs through Name Resolver / Node Normalizer.
• Lazily caches Translator API metadata.
• Returns parsed FinderResult objects with direct access to query, KG, results, auxiliary graphs, resolved nodes, and raw output.

Fixes

• Places TRAPI attribute_constraints on the query edge (edges.e00) instead of as an invalid sibling under edges.

Docs

• Adds notebooks/Experimental_API_tutorial.ipynb.
• Adds README pointers to the new experimental tutorial.
• Keeps links to legacy notebooks for fine-grained endpoint, predicate, query, parser, and visualization control.

Tests

• Adds mocked unit coverage for the experimental API.
• Updates Node Normalizer tests.
• Verified with uv run pytest tests/test_experimental.py and uv run pytest.

[yjzhang]

Is it really necessary to change all the single quotes to double quotes in tests/test_nodenorm.py? Otherwise, this looks good! In the future (not in this PR) we might want to merge the experimental API with the current pathfinder/neighborhood finder.

[SkyeAv]

The change to double quotes aren't tests/test_nodenorm.py necessary, they're just an artifact of my IDE. If y'all want I can boot up a different IDE and revert the change? I think they're harmless for now.

Also, I 100% agree that it makes sense to eventually merge the experimental and main APIs. I thought it would be good to get people using the new ones for a little to iron out any kinks before we commit to the switch.