Cleanup & Pre-release Checks

Summary

This PR completes the tfe → pytfe rename, finalizes the modular model layout under pytfe/models/, and hardens the transport and resources to prep for GA. Highlights:

• Switch imports to pytfe across source, tests, and examples.
• Split the former monolithic types.py into cohesive domain modules under pytfe/models/ (with a new common.py).
• Establish a curated public facade via pytfe/models/__init__.py (no more dynamic loaders).
• Align resource option handling and examples with the new model layout.
• Pre-GA transport cleanup (headers, config surfaces), plus follow-ups called out below.

Notable Changes

1) Package rename & public surface

• All imports moved from tfe → pytfe.
• src/pytfe/__init__.py exposes a minimal, stable surface: TFEClient, TFEConfig, errors, models.
• pyproject.toml: distribution name set to pytfe, wheel target src/pytfe, sdist include list updated.
• Examples/tests updated to import from the new namespace.

2) Model refactor (types split → modules)

Why: smaller units, clearer ownership, better testability, fewer circulars.

• pytfe/models/common.py: shared primitives & small types (e.g., enums, pagination, tag-related helpers) to avoid duplication and cross-module import cycles.
• Configuration versions → models/configuration_version.py (includes ConfigurationVersion* models, IngressAttributes, and ConfigVerIncludeOpt).
• Data retention policy → models/data_retention_policy.py (policy + set options + choice union).
• Workspaces → models/workspace.py (workspace DTOs, options, include enums, VCSRepo, LockedByChoice, etc.).
• Projects / Variables / Variable sets / Registry modules / Providers / OAuth / Agents / SSH keys / Reserved tag keys / Query runs split into corresponding domain modules.
• models/__init__.py: curated, explicit re-exports from domain modules; removed dynamic importlib loader that used to reflect a flat types.py.

Foundation: All new types live in a domain module under pytfe/models/ and are re-exported intentionally from pytfe/models/__init__.py. No dynamic imports.

3) Transport groundwork

• Unified User-Agent string set to pytfe/<version>.
• Transport constructor kept stable; follow-up below to finalize proxy handling.

Foundations for the Team (to keep going forward)

1. Module boundaries & re-exports

   • Domain modules own their types.
   • pytfe/models/__init__.py is the only public exporter—keep it curated and alphabetized.
   • No dynamic type loading.

2. Transport contracts

   • All services depend on a single HTTPTransport. (No Async)

Testing

• Unit tests updated to pytfe imports and new model paths.

Appendix: Example import patterns

# Public surface for users
from pytfe import TFEClient, TFEConfig
from pytfe.models import WorkspaceCreateOptions, Workspace

# Internal (inside the package), relative imports from defining modules
from ..models.workspace import WorkspaceListOptions