feat(arcade-core): add CONTACTS service domain (TOO-1322)

[samkujovich]

What

Adds a CONTACTS member to ServiceDomain (arcade_core.metadata, re-exported via arcade_mcp_server.metadata):

CONTACTS = "contacts"
"""Address books and people directories — managing personal or organizational contact records."""

Why

The google_contacts toolkit is the only Google toolkit in the monorepo with no ServiceDomain — every sibling sets one (gmail→EMAIL, calendar→CALENDAR, docs→DOCUMENTS, drive→CLOUD_STORAGE, sheets→SPREADSHEETS, slides→PRESENTATIONS). No existing value fits an address book:

• CRM fails the 10/10 test — Google Contacts is a personal/org address book, not a sales-pipeline CRM (Salesforce/HubSpot/Attio).
• SALES_INTELLIGENCE is prospecting/lead databases (Apollo), not a personal/org directory.

Per the metadata convention (the Datadog → OBSERVABILITY / Apollo → SALES_INTELLIGENCE precedent), when no ServiceDomain fits a recognized external service, add one upstream rather than force a wrong category.

Changes

• ServiceDomain.CONTACTS = "contacts" with a docstring, placed next to CRM so the distinction is explicit.
• A test asserting the enum value and a classified-tool round-trip (mirrors test_decorator_accepts_sales_intelligence_domain).

No version bump (consistent with the prior service-domain additions; handled at release).

Test plan

• uv run pytest -W ignore libs/tests/tool/test_tool_metadata.py libs/tests/arcade_mcp_server/test_tool_metadata_serialization.py — 61 passed (incl. new test_decorator_accepts_contacts_domain)

Downstream

Unblocks TOO-1322 in the monorepo: once released, bump arcade-mcp-server in google_contacts and classify its 5 tools with ServiceDomain.CONTACTS.

Refs: TOO-1322

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Note

Low Risk
Additive enum and test only; no changes to auth, runtime behavior, or existing tool metadata rules.

Overview
Adds ServiceDomain.CONTACTS ("contacts") to arcade_core.metadata, positioned next to CRM, for address books and people directories (e.g. Google Contacts) rather than sales CRM or prospecting tools.

A new decorator test checks the enum value and that tools can classify with CONTACTS end-to-end, matching the existing SALES_INTELLIGENCE pattern. No validation or serialization logic changes beyond the new enum member.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
libs/arcade-core/arcade_core/metadata.py	100.00% <100.00%> (ø)

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[jottakka]

Needs a version bump! Dont forget to set the proper depedency version in the toolkit that you will added this as well.