refactor: flip spine to NemoClient + swap all SDK imports

[maxdubrinsky]

Summary

Flip sdk_factory to return NemoClient/AsyncNemoClient instead of NeMoPlatform/AsyncNeMoPlatform. Rewrite the bridge adapter to use from_client() instead of reading Stainless private attrs. Swap all 528 consumer files from from nemo_platform imports to typed client imports. Type annotations changed throughout (NeMoPlatform -> NemoClient, AsyncNeMoPlatform -> AsyncNemoClient).

Method calls use new typed client method names (get_workspace, create_guardrail_config, etc.) from PR 1. Old method names are also available via the compat layer from PR 2.

Related Issue

AIRCORE-827

Changes

• sdk_factory.py: Spine flip — returns NemoClient/AsyncNemoClient, PlatformClientT TypeVar bound to typed clients, URL resolver adapted
• adapter.py: Rewritten to use ClientCls.from_client(platform) instead of reading Stainless private attrs (_custom_headers, _client, _prepare_url, etc.)
• 528 consumer files: Import swaps (from nemo_platform -> typed client modules), type annotation changes, method name renames (old SDK names -> new typed client names)
• 24 files left as-is: Still import from nemo_platform (enhanced NeMoPlatform client, error handlers, code generators, pagination types). The SDK is still present, so these imports work. Full migration happens when the code generators are updated and the SDK is deleted (PR 10).
• Pyproject.toml files NOT changed: SDK deps kept since the SDK is still present. Removal happens in PR 10.

Type of Change

• Code change (feature, bug fix, or refactor)
• Code change with documentation updates
• Documentation only
• Contributor tooling or automation
• CI, build, or test infrastructure

Quality Gates

• Tests added or updated for changed behavior
• Existing tests cover changed behavior — justification: mechanical import/type swaps; behavior unchanged
• Tests not applicable — justification:
• Documentation updated for user-visible behavior
• Documentation not applicable — justification: internal refactoring, no user-visible API change

Verification

• Pull request title follows the repository's Conventional Commit format
• Every commit includes an appropriate Signed-off-by: trailer
• uv run pre-commit run -a passes, or any blocked checks are identified below
• Targeted tests pass, or tests are marked not applicable above
• No secrets, API keys, or credentials are included

Targeted validation:

• py_compile on all 528 modified .py files: all compile (syntax OK)
• DCO audit: 5 commits, all sign-offs match author email
• Pre-commit, ruff, and targeted pytest not yet run in the worktree (draft); will run before marking ready for review
• 24 files with remaining from nemo_platform imports are expected (SDK still present)

Stack

PR 3 of the Stainless purge stack:

• PR 1 (feat(client): add typed clients for remaining service areas + NemoClient compat layer #1465): Typed clients + NemoClient convenience properties
• PR 2 (feat(client): add backward-compat layer for Stainless SDK method names #1481): Backward-compat layer for old SDK method names
• PR 3 (this): Spine flip + import swaps + method renames
• PR 10: Delete SDK + pyproject cleanup (depends on this PR)
• PR 9: Remove compat aliases (depends on this PR merging to main)

Note: The original plan had PRs 4-8 (per-area method renames) branching from PR 3. Since the exploration's files already include method renames alongside import swaps, those are folded into PR 3. The plan simplifies from 10 PRs to 5.

[github-actions]

🌿 Preview your docs: https://nvidia-preview-pr-1482-aircore-827-spine-flip-mdubrinsky.docs.buildwithfern.com/nemo-platform

[maxdubrinsky]

Closing in favor of area-by-area consumer migration approach (migrate consumers first via client_from_platform, flip spine last). The compat layer and big-bang spine flip are unnecessary.