feat(circles): create_circle + add_member_to_circle (v0.7.0)

- acccreatefamily endpoint creates a new circle (returns numeric ID)
- accinvite endpoint invites new users by email (familyId, identifier, role, firstname)
- fw_client now detects a00.ex errors (was only checking a00.un before)
- New modules/circles.py with FamilyRoleTypeEnum constants
- SPEC.md updated with acccreatefamily, accinvite, accupdatefamily docs
- Note: circle deletion not supported by FW API (metadelete → "delete not supported")
- Note: accinvite only works for new (non-existing) FW accounts

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "mcp-familywall"
-version = "0.6.1"
+version = "0.7.0"
 description = "MCP server for Family Wall — read your family's lists and tasks via Claude"
 readme = "README.md"
 requires-python = ">=3.12"