fix: route all agent loopback calls through internal_api_base() helper (#3322)

#2753 made the agent loopback base port-configurable but only for
_COOKBOOK_BASE in tool_implementations. Several other in-process loopback
calls still hardcoded http://localhost:7000 and broke off port 7000:
cookbook_serve_lifecycle (model-endpoints x2, shell/exec), builtin_actions
(model/serve), task_routes (calendar x3), and the gallery/email calls in
tool_implementations.

Extract the resolution (ODYSSEUS_INTERNAL_BASE / APP_PORT / 7000 fallback,
127.0.0.1 to avoid IPv6 ambiguity) into core.constants.internal_api_base()
and route every call site through it. Rename the now-misnamed _COOKBOOK_BASE
to _INTERNAL_BASE since it serves gallery/email/calendar/serve too. Adds a
test for the resolver plus a regression guard against reintroducing the
literal.

Part of #2752.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

src/cookbook_serve_lifecycle.py

@@ -19,6 +19,7 @@ import time
 from pathlib import Path
 
 import httpx
+from core.constants import internal_api_base
 
 logger = logging.getLogger(__name__)
 
@@ -58,7 +59,7 @@ async def _delete_endpoint_for_task(task: dict) -> None:
     try:
         async with httpx.AsyncClient(timeout=8) as client:
             r = await client.get(
-                "http://localhost:7000/api/model-endpoints",
+                f"{internal_api_base()}/api/model-endpoints",
                 headers=_internal_headers(),
             )
             if r.status_code >= 400:
@@ -73,7 +74,7 @@ async def _delete_endpoint_for_task(task: dict) -> None:
                 ep = next((e for e in eps if hostport in (e.get("base_url") or "")), None)
             if ep:
                 await client.delete(
-                    f"http://localhost:7000/api/model-endpoints/{ep['id']}",
+                    f"{internal_api_base()}/api/model-endpoints/{ep['id']}",
                     headers=_internal_headers(),
                 )
                 logger.info(
@@ -108,7 +109,7 @@ async def _stop_serve(session_id: str, remote_host: str = "", ssh_port: str = ""
     try:
         async with httpx.AsyncClient(timeout=15) as client:
             r = await client.post(
-                "http://localhost:7000/api/shell/exec",
+                f"{internal_api_base()}/api/shell/exec",
                 json={"command": cmd},
                 headers=_internal_headers(),
             )