[test] MCP crate severely under-tested

`edda-mcp` has 7 tool endpoints + 2 resources but only 3 tests that check static server metadata.

None of the actual tool implementations are tested:
- `edda_status`
- `edda_note`
- `edda_context`
- `edda_decide`
- `edda_ask`
- `edda_log`
- `edda_draft_inbox`
- `edda_tool_tier`