feat(server): guide automatic memory capture

[ramonlimaramos]

Summary

• expand remember tool description with durable-memory triggers, memory_type guidance, and depth_layer guidance
• expand recall tool description to encourage proactive context loading before non-trivial tasks
• document default memory routing patterns in the README
• add tests that lock the automatic-capture guidance into MCP tool descriptions

Release plan

• Target: v0.5.0 source-of-truth / governed context layer
• Closes [feature] automatic memory capture — llm should use synapto as default memory system #7

Validation

• git diff --check
• uv run pytest tests/unit/test_tool_metadata.py tests/unit/test_server_instructions.py -q (25 passed)
• uv run pytest tests/unit -q (238 passed)
• uv run ruff check src/ tests/
• GitHub CI run 27515390795: lint, security, test 3.11, test 3.12, test 3.13 all passed