refactor(clients): drop the POC operator methods that never had an operator behind them

[jfrench9]

Summary

Removes three facade methods that never had an operator behind them. OperatorClient.analyze_financials(), .research(), and .rag() (plus the module-level analyze_financials convenience) sent operator_type = financial / research / rag — none of which has ever been registered on the API (only cypher, now analyst, and mapping exist), so every call 404'd. They were early-POC placeholders that survived into the facade.

Changes

• robosystems_client/clients/operator_client.py — removed analyze_financials, research, rag. query() (auto-select) and execute_operator(graph_id, operator_type, …) remain the surface; nothing else in the class changed.
• robosystems_client/clients/__init__.py — removed the module-level analyze_financials convenience (it was never in __all__).
• tests/test_operator_client.py — removed the three tests that pinned the dead methods. The generic execute_operator tests keep their placeholder type strings; they exercise the pass-through, not a real operator.

Sync and async: the facade is sync-only; no async counterpart existed.

Compatibility

By the template's letter this is BREAKING (removed exports). It ships under the SDK contract's dead-surface carve-out — a client minor, no deprecation cycle — because all three conditions hold: (1) the methods never functioned in any shipped configuration (the operator types were never registered; every call returned 404); (2) no consumer exists — none of the three apps, robosystems-core, robosystems-integration-template, or robosystems-demo-integration references them; (3) removal changes symbol resolution only — no working call's behavior changes. A consumer that somehow called them has a 404 today and an AttributeError after; the fix in both cases is execute_operator(graph_id, "analyst", …) or query().

Testing

• just test-all — pytest 523 passed / 17 skipped, ruff check + format clean, basedpyright 0 errors. Pre-commit hook ran the same set.