Add zep-ag2 package providing Zep memory integration for AG2
(community AutoGen fork, 400K+ monthly PyPI downloads).

Key design: AG2 has no formal Memory base class like MS AutoGen v4,
so the integration uses composition — tool factories for
@register_for_llm/@register_for_execution and ZepMemoryManager
for system message injection.

Tools are synchronous (AG2 executes tools synchronously) with a
background event loop for async Zep SDK calls. Each tool coroutine
creates its own AsyncZep instance to avoid event-loop binding issues.

- ZepMemoryManager: system message injection + conversation memory
- ZepGraphMemoryManager: knowledge graph operations
- 4 tool factories: search_memory, add_memory, search_graph, add_graph_data
- register_all_tools() convenience function
- 66 tests, 96% coverage
- 4 examples + manual integration test

…ations/ag2/python

Relocates the AG2 integration to the platform-first path and applies
code-review fixes:

- Fix Python 3.13 sync-bridge crash: replace asyncio.get_event_loop() in the
  manager sync wrappers with a shared _run_sync() that submits coroutines to a
  single daemon background event loop via run_coroutine_threadsafe.
- Eliminate the per-call AsyncZep leak and private _client_wrapper.api_key
  access: tools now reuse the caller-supplied AsyncZep, driven on the shared
  background loop (verified httpx loop affinity allows this).
- Never log message content / raw exceptions: log type(e).__name__ only and
  return generic, non-leaking error strings; keep graceful degradation.
- Make the dependency guard truthful: verify `import autogen` (AG2) at import.
- Add message (4000) and graph-data (9900) size guards with truncate-and-warn
  (lengths only) across tools and ZepMemoryManager.add_messages.
- register_all_tools: register each uniquely-named tool once for LLM and once
  for execution (no duplicate-execution override warnings).
- Validate/normalize message roles to the Zep RoleType set (default assistant).
- Guard graph node summary None -> "No summary".
- Drop the redundant thread.get(lastn=10) read in get_memory_context.
- Align scope handling between create_search_memory_tool and
  create_search_graph_tool.
- Thread-safe lazy background-loop init with documentation and an optional
  shutdown_background_loop() helper.
- Docs/metadata: add SETUP.md; fix README (Python 3.11+, zep-cloud>=3.23.0,
  reworked background-loop copy); single coherent CHANGELOG 0.1.0 entry;
  pyproject classifiers, authors, keywords.
- Tests: exercise the real client-reuse path (no per-call construction, no
  _client_wrapper access), the 3.11-3.13 sync bridge, size truncation, role
  validation, and override-free registration.

Validation (Python 3.11/3.12/3.13): ruff check, ruff format --check, mypy
src/, and pytest tests/ (83 passed) all green; the 4 previously-failing
sync-wrapper tests now pass on 3.13.

Co-Authored-By: faridun-ag2 <faridun-ag2@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>