Release title: v2.0.4 — Legacy client cleanup, test fixes, docs overhaul

What's Changed

Added

• example_14_low_level_adi_creation.py — complete ADI creation flow using only raw binary encoding (no SmartSigner or TxBody), verified end-to-end
  on Kermit testnet. Every block annotates where convenience methods replace 20+ lines with 2-4 lines.
• Convenience method reference tables in all documentation files (README, ZERO_TO_HERO, examples/README, src/README)
• SDK API levels documentation — explains the three levels (QuickStart / SmartSigner+TxBody / Raw Binary Encoding) and exactly what each convenience
  method does under the hood

Fixed

• Resolved all 31 xfailed tests — incorrect factory data types for SendTokens, AddCredits, UpdateKeyPage, TransferCredits, UpdateAccountAuth, NetworkMaintenance, CreateLiteDataAccount
• Fixed _restore_field_types() to handle Optional[bytes], aliased Pydantic fields, and nested List[Union[BaseModel,...]] with type discriminators
• Fixed build_envelope() missing signatures key
• Fixed validation.py using newKey instead of newKeyHash for UpdateKey
• Deleted orphaned tests for removed legacy modules and scripts

Changed

• Removed legacy client modules: api_client.py, client.py, json_rpc_client.py, generated_client.py, client_compat.py, client_mock.py, client_test.py — all functionality is covered by facade.py + v2/ + v3/
• All docs updated with correct git clone URL, package name disambiguation (accumulate-sdk-opendlt vs old accumulate-python-client), and SmartSigner/TxBody/QuickStart explanations
• Examples 01 and 02 annotated with inline comments explaining convenience methods

Test Results

• 2354 passed, 14 skipped, 0 xfailed, 0 failed
• 14 skips are legitimate (DevNet not running, optional deps not installed).

Full Changelog: opendlt/accumulate-python-client@v2.0.3...v2.0.4