feat(enterprise): add multi-PSA adapter stubs for Autotask and Halo PSA

- Create AutotaskProvider stub with all abstract methods raising NotImplementedError
- Create HaloPSAProvider stub with all abstract methods raising NotImplementedError
- Add PSA provider grid in IntegrationsPage showing ConnectWise (active),
  Autotask (Coming Soon), and Halo PSA (Coming Soon) with appropriate badges

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/services/psa/autotask/__init__.py

@@ -0,0 +1,3 @@
+from app.services.psa.autotask.provider import AutotaskProvider
+
+__all__ = ["AutotaskProvider"]

backend/app/services/psa/autotask/provider.py

@@ -0,0 +1,72 @@
+"""Autotask PSA provider stub. Full implementation planned for Phase 5."""
+from __future__ import annotations
+
+from app.services.psa.base import PSAProvider
+from app.services.psa.types import (
+    ConnectionTestResult,
+    PSATicket,
+    PSANote,
+    PSAStatus,
+    PSACompany,
+    PSAMember,
+    PSAConfiguration,
+    PSATimeEntry,
+)
+
+
+class AutotaskProvider(PSAProvider):
+    """Stub provider for Autotask PSA. All methods raise NotImplementedError.
+
+    Full implementation is planned for Phase 5. This stub allows the provider
+    to be registered and discovered without causing import errors.
+    """
+
+    async def test_connection(self) -> ConnectionTestResult:
+        raise NotImplementedError("Autotask integration coming soon")
+
+    async def get_ticket(self, ticket_id: str) -> PSATicket:
+        raise NotImplementedError("Autotask integration coming soon")
+
+    async def search_tickets(self, query: str, **filters) -> list[PSATicket]:
+        raise NotImplementedError("Autotask integration coming soon")
+
+    async def post_note(
+        self,
+        ticket_id: str,
+        text: str,
+        note_type: str,
+        member_id: str | None = None,
+    ) -> PSANote:
+        raise NotImplementedError("Autotask integration coming soon")
+
+    async def update_ticket_status(
+        self,
+        ticket_id: str,
+        status_id: int,
+    ) -> PSATicket:
+        raise NotImplementedError("Autotask integration coming soon")
+
+    async def get_ticket_statuses(self, board_id: int) -> list[PSAStatus]:
+        raise NotImplementedError("Autotask integration coming soon")
+
+    async def list_companies(self, **filters) -> list[PSACompany]:
+        raise NotImplementedError("Autotask integration coming soon")
+
+    async def get_company(self, company_id: str) -> PSACompany:
+        raise NotImplementedError("Autotask integration coming soon")
+
+    async def list_members(self) -> list[PSAMember]:
+        raise NotImplementedError("Autotask integration coming soon")
+
+    async def get_ticket_configurations(self, ticket_id: str) -> list[PSAConfiguration]:
+        raise NotImplementedError("Autotask integration coming soon")
+
+    async def create_time_entry(
+        self,
+        ticket_id: str,
+        member_id: str,
+        hours: float,
+        notes: str | None = None,
+        work_type: str | None = None,
+    ) -> PSATimeEntry:
+        raise NotImplementedError("Autotask integration coming soon")

backend/app/services/psa/halopsa/__init__.py

@@ -0,0 +1,3 @@
+from app.services.psa.halopsa.provider import HaloPSAProvider
+
+__all__ = ["HaloPSAProvider"]

backend/app/services/psa/halopsa/provider.py

@@ -0,0 +1,72 @@
+"""Halo PSA provider stub. Full implementation planned for Phase 5."""
+from __future__ import annotations
+
+from app.services.psa.base import PSAProvider
+from app.services.psa.types import (
+    ConnectionTestResult,
+    PSATicket,
+    PSANote,
+    PSAStatus,
+    PSACompany,
+    PSAMember,
+    PSAConfiguration,
+    PSATimeEntry,
+)
+
+
+class HaloPSAProvider(PSAProvider):
+    """Stub provider for Halo PSA. All methods raise NotImplementedError.
+
+    Full implementation is planned for Phase 5. This stub allows the provider
+    to be registered and discovered without causing import errors.
+    """
+
+    async def test_connection(self) -> ConnectionTestResult:
+        raise NotImplementedError("Halo PSA integration coming soon")
+
+    async def get_ticket(self, ticket_id: str) -> PSATicket:
+        raise NotImplementedError("Halo PSA integration coming soon")
+
+    async def search_tickets(self, query: str, **filters) -> list[PSATicket]:
+        raise NotImplementedError("Halo PSA integration coming soon")
+
+    async def post_note(
+        self,
+        ticket_id: str,
+        text: str,
+        note_type: str,
+        member_id: str | None = None,
+    ) -> PSANote:
+        raise NotImplementedError("Halo PSA integration coming soon")
+
+    async def update_ticket_status(
+        self,
+        ticket_id: str,
+        status_id: int,
+    ) -> PSATicket:
+        raise NotImplementedError("Halo PSA integration coming soon")
+
+    async def get_ticket_statuses(self, board_id: int) -> list[PSAStatus]:
+        raise NotImplementedError("Halo PSA integration coming soon")
+
+    async def list_companies(self, **filters) -> list[PSACompany]:
+        raise NotImplementedError("Halo PSA integration coming soon")
+
+    async def get_company(self, company_id: str) -> PSACompany:
+        raise NotImplementedError("Halo PSA integration coming soon")
+
+    async def list_members(self) -> list[PSAMember]:
+        raise NotImplementedError("Halo PSA integration coming soon")
+
+    async def get_ticket_configurations(self, ticket_id: str) -> list[PSAConfiguration]:
+        raise NotImplementedError("Halo PSA integration coming soon")
+
+    async def create_time_entry(
+        self,
+        ticket_id: str,
+        member_id: str,
+        hours: float,
+        notes: str | None = None,
+        work_type: str | None = None,
+    ) -> PSATimeEntry:
+        raise NotImplementedError("Halo PSA integration coming soon")