v0.1.8

Breaking Change

• quiz_create now accepts difficulty: str ("easy"|"medium"|"hard") instead of int (1|2|3)

Added

• constants.py module as single source of truth for all API code-name mappings
• CodeMapper class with bidirectional lookup (name→code, code→name)
• Dynamic error messages now show valid options from CodeMapper
• uv.lock committed for supply chain security

Changed

• All MCP tools now use constants.CodeMapper for input validation
• All API client output now uses constants.CodeMapper for human-readable names
• Removed ~10 static _get_*_name helper methods from api_client.py
• Removed duplicate *_codes dictionaries from server.py tool functions

Fixed

• Removed duplicate code block in research status parsing

Docs

• Updated comprehensive cleanup tests in MCP_TEST_PLAN.md (Tests 10.1-10.7)
• Added constants.py to architecture docs