Split heavy adapter-integration deps out of [dev] to unblock Python 3.14 support

Problem

The library targets 3.14-compatible code, but the [dev] extra's heavy adapter-integration tree (crewai, mem0ai, fastmcp, langgraph, langchain-core) caps at Requires-Python <3.14, so the CI matrix cannot add a 3.14 cell — the test tooling, not the library, blocks 3.14 support. The ci.yml comment already concedes this. The same tree also inflates every matrix cell's install and has broken the type gate before (the numpy mypy override is a scar from it).

Evidence

• .github/workflows/ci.yml:26-33 (comment explaining the 3.14 exclusion).
• pyproject.toml:88-132 ([dev] contents).
• uv.lock resolves 409 packages for this project.

Proposed scope

• Split adapter-integration deps into a [dev-adapters] extra installed on one representative cell (3.12, where the other single-cell gates already live).
• Keep the pure [dev] matrix resolvable on 3.14 and add the 3.14 gating cell.

Acceptance criteria

• 3.14 gating cell is green.
• Adapter-integration tests still run on the 3.12 cell.

Related

#653 (developer test-loop cost), #751 (CI-dark adapters — the extras job there can share the split).

Filed from the 2026-07-03 read-only repository audit (evidence verified at v0.16.0, commit 9f3bc7f).

Start with .github/workflows/ci.yml:26-33 and pyproject.toml:88-132, then inspect uv.lock to understand the current dependency resolution. Trace which adapter-integration tests and gates run on each matrix cell. Done means the 3.14 gating cell is green while adapter-integration tests still run on the 3.12 cell.