Replace inter-service _handlers dicts with declarative sx defquery/defaction

The inter-service data layer (fetch_data/call_action) was the least
structured part of the codebase — Python _handlers dicts with ad-hoc
param extraction scattered across 16 route files. This replaces them
with declarative .sx query/action definitions that make the entire
inter-service protocol self-describing and greppable.

Infrastructure:
- defquery/defaction special forms in the sx evaluator
- Query/action registry with load, lookup, and schema introspection
- Query executor using async_eval with I/O primitives
- Blueprint factories (create_data_blueprint/create_action_blueprint)
  with sx-first dispatch and Python fallback
- /internal/schema endpoint on every service
- parse-datetime and split-ids primitives for type coercion

Service extractions:
- LikesService (toggle, is_liked, liked_slugs, liked_ids)
- PageConfigService (ensure, get_by_container, get_by_id, get_batch, update)
- RelationsService (wraps module-level functions)
- AccountDataService (user_by_email, newsletters)
- CartItemsService, MarketDataService (raw SQLAlchemy lookups)

50 of 54 handlers converted to sx, 4 Python fallbacks remain
(ghost-sync/push-member, clear-cart-for-order, create-order).
Net: -1,383 lines Python, +251 lines modified.

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

blog/bp/actions/routes.py

@@ -1,96 +1,14 @@
 """Blog app action endpoints.
 
-Exposes write operations at ``/internal/actions/<action_name>`` for
-cross-app callers via the internal action client.
+All actions are defined in ``blog/actions.sx``.
 """
 from __future__ import annotations
 
-from quart import Blueprint, g, jsonify, request
+from quart import Blueprint
 
-from shared.infrastructure.actions import ACTION_HEADER
+from shared.infrastructure.query_blueprint import create_action_blueprint
 
 
 def register() -> Blueprint:
-    bp = Blueprint("actions", __name__, url_prefix="/internal/actions")
-
-    @bp.before_request
-    async def _require_action_header():
-        if not request.headers.get(ACTION_HEADER):
-            return jsonify({"error": "forbidden"}), 403
-        from shared.infrastructure.internal_auth import validate_internal_request
-        if not validate_internal_request():
-            return jsonify({"error": "forbidden"}), 403
-
-    _handlers: dict[str, object] = {}
-
-    @bp.post("/<action_name>")
-    async def handle_action(action_name: str):
-        handler = _handlers.get(action_name)
-        if handler is None:
-            return jsonify({"error": "unknown action"}), 404
-        result = await handler()
-        return jsonify(result or {"ok": True})
-
-    # --- update-page-config ---
-    async def _update_page_config():
-        """Create or update a PageConfig (page_configs now lives in db_blog)."""
-        from shared.models.page_config import PageConfig
-        from sqlalchemy import select
-        from sqlalchemy.orm.attributes import flag_modified
-
-        data = await request.get_json(force=True)
-        container_type = data.get("container_type", "page")
-        container_id = data.get("container_id")
-        if container_id is None:
-            return {"error": "container_id required"}, 400
-
-        pc = (await g.s.execute(
-            select(PageConfig).where(
-                PageConfig.container_type == container_type,
-                PageConfig.container_id == container_id,
-            )
-        )).scalar_one_or_none()
-
-        if pc is None:
-            pc = PageConfig(
-                container_type=container_type,
-                container_id=container_id,
-                features=data.get("features", {}),
-            )
-            g.s.add(pc)
-            await g.s.flush()
-
-        if "features" in data:
-            features = dict(pc.features or {})
-            for key, val in data["features"].items():
-                if isinstance(val, bool):
-                    features[key] = val
-                elif val in ("true", "1", "on"):
-                    features[key] = True
-                elif val in ("false", "0", "off", None):
-                    features[key] = False
-            pc.features = features
-            flag_modified(pc, "features")
-
-        if "sumup_merchant_code" in data:
-            pc.sumup_merchant_code = data["sumup_merchant_code"] or None
-        if "sumup_checkout_prefix" in data:
-            pc.sumup_checkout_prefix = data["sumup_checkout_prefix"] or None
-        if "sumup_api_key" in data:
-            pc.sumup_api_key = data["sumup_api_key"] or None
-
-        await g.s.flush()
-
-        return {
-            "id": pc.id,
-            "container_type": pc.container_type,
-            "container_id": pc.container_id,
-            "features": pc.features or {},
-            "sumup_merchant_code": pc.sumup_merchant_code,
-            "sumup_checkout_prefix": pc.sumup_checkout_prefix,
-            "sumup_configured": bool(pc.sumup_api_key),
-        }
-
-    _handlers["update-page-config"] = _update_page_config
-
+    bp, _handlers = create_action_blueprint("blog")
     return bp