feat: complete core runtime hooks

[wxai-space]

Summary

• add after_run and on_error hooks to close the core LightAgent lifecycle
• add before_memory_retrieve and after_memory_retrieve hooks around memory reads
• route terminal errors, guardrail/hook blocks, and recoverable tool errors through on_error
• update runtime hook docs, README hook phase list, roadmap, and package version to 0.9.2

Notes

• on_handoff is intentionally left for a later version, matching the requested priority.
• v0.9.1 has already been released, so this completion work is prepared as v0.9.2 instead of mutating the released tag.
• Local untracked dist/ and tests/ files were not included.

Validation

• /Users/macpro/opt/anaconda3/envs/Langchain-Chatchat/bin/python -m compileall LightAgent
• /Users/macpro/opt/anaconda3/envs/Langchain-Chatchat/bin/python -m pytest -q tests/test_v070_tracing.py tests/test_memory_policy.py tests/test_lightflow.py tests/test_litellm_client.py tests/test_mcp_client_manager.py tests/test_v065_core.py tests/test_guardrails.py tests/test_shared_memory_pool.py tests/test_skill_manager_logging.py tests/test_vector_memory_adapter_example.py
• Result: 70 passed