feat: update all database adapters to use cognee 1.6.1

[ArmagedonFlamer]

Resolves SDK-857. Moves every graph, vector and hybrid adapter from cognee 1.4.2 to 1.6.1. Supersedes #190: its four commits are cherry-picked here with authorship kept, so #190 can be closed.

What changed between 1.5.4 and 1.6.1 for adapters

• The required methods of GraphDBInterface / VectorDBInterface are unchanged, and so are the factory constructor kwargs. The call shapes cognee core uses are also unchanged.
• Removed: get/set_node_frequency_weights and get/set_edge_frequency_weights. No adapter implemented them.
• New optional hooks, with working defaults: get_top_degree_node_ids, iter_bounded_neighborhood, get_entity_type_names (graph) and score_by_ids (vector). No community adapter overrides them yet.
• The built-in Postgres graph adapter is now postgres_demo.PostgresDemoAdapter.

Changes

• cognee==1.6.1 pinned in all 24 adapter packages. pggraph and typedb were still on 1.4.2. litellm stays at 1.96.2, which is what 1.6.1 locks.
• pggraph: rebased on PostgresDemoAdapter. The pgGraph setup now runs once per adapter, because the base class calls initialize() from most of its methods. The SQL neighborhood fallback now delegates to the base get_neighborhood; the text[] cast workaround is no longer needed.
• typedb:
  • Dropped ladybug<0.18, which can't resolve alongside cognee 1.6.1's ladybug==0.19.0 on Linux.
  • Removed the frequency-weights test and README note.
  • Ported upstream's new test_concurrent_folded_writes_and_attaches_keep_every_owner provenance contract test.
• Contract suite: now cites the 1.6.1 call sites, and checks the call shape of the new optional hooks whenever an adapter overrides one.
• Package versions: patch bumps. None of feat: update all database adapters to use cognee 1.5.4 #190's versions were ever published. opensearch goes to 1.0.1 because PyPI already has 1.0.0. typedb stays at 0.1.0 since it is unpublished.
• All uv.lock and poetry.lock files regenerated (Poetry 2.4.1, matching the existing locks). READMEs and .github/workflows/README.md updated.

Verified locally

• ruff check and ruff format --check: clean.
• tests/unit for all 24 adapters on Python 3.11 with cognee 1.6.1: all pass.
• pggraph tests/test_pggraph.py against postgres:16 with COGNEE_PGGRAPH_TESTS=true: 16 passed.
• typedb tests/unit tests/integration against typedb/typedb:3.12.3: 109 passed.

Not run locally: the other adapters' integration and e2e tiers, which need their services or LLM secrets. Those are left to CI.

Follow-ups (not in this PR)

• Native get_top_degree_node_ids / iter_bounded_neighborhood for graph backends that can bound the read server-side, and score_by_ids for vector stores that can filter by ID.
• Publishing the new versions to PyPI.

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