feat: add Google Contacts (People API) support

Add 16 MCP tools for managing Google Contacts via the People API:

Core tier:
- list_contacts, get_contact, search_contacts, create_contact

Extended tier:
- update_contact, delete_contact, list_contact_groups, get_contact_group

Complete tier:
- batch_create_contacts, batch_update_contacts, batch_delete_contacts
- create_contact_group, update_contact_group, delete_contact_group
- modify_contact_group_members

Includes:
- OAuth scopes for contacts and contacts.readonly
- People API service configuration
- Tool tier definitions
- Unit tests for helper functions

auth/scopes.py

@@ -61,6 +61,10 @@ SLIDES_READONLY_SCOPE = "https://www.googleapis.com/auth/presentations.readonly"
 TASKS_SCOPE = "https://www.googleapis.com/auth/tasks"
 TASKS_READONLY_SCOPE = "https://www.googleapis.com/auth/tasks.readonly"
 
+# Google Contacts (People API) scopes
+CONTACTS_SCOPE = "https://www.googleapis.com/auth/contacts"
+CONTACTS_READONLY_SCOPE = "https://www.googleapis.com/auth/contacts.readonly"
+
 # Google Custom Search API scope
 CUSTOM_SEARCH_SCOPE = "https://www.googleapis.com/auth/cse"
 
@@ -109,6 +113,8 @@ SLIDES_SCOPES = [SLIDES_SCOPE, SLIDES_READONLY_SCOPE]
 
 TASKS_SCOPES = [TASKS_SCOPE, TASKS_READONLY_SCOPE]
 
+CONTACTS_SCOPES = [CONTACTS_SCOPE, CONTACTS_READONLY_SCOPE]
+
 CUSTOM_SEARCH_SCOPES = [CUSTOM_SEARCH_SCOPE]
 
 SCRIPT_SCOPES = [
@@ -132,6 +138,7 @@ TOOL_SCOPES_MAP = {
     "forms": FORMS_SCOPES,
     "slides": SLIDES_SCOPES,
     "tasks": TASKS_SCOPES,
+    "contacts": CONTACTS_SCOPES,
     "search": CUSTOM_SEARCH_SCOPES,
     "appscript": SCRIPT_SCOPES,
 }