Add macros, declarative handlers (defhandler), and convert all fragment routes to sx

Phase 1 — Macros: defmacro + quasiquote syntax (`, ,, ,@) in parser,
evaluator, HTML renderer, and JS mirror. Macro type, expansion, and
round-trip serialization.

Phase 2 — Expanded primitives: app-url, url-for, asset-url, config,
format-date, parse-int (pure); service, request-arg, request-path,
nav-tree, get-children (I/O); jinja-global, relations-from (pure).
Updated _io_service to accept (service "registry-name" "method" :kwargs)
with auto kebab→snake conversion. DTO-to-dict now expands datetime fields
into year/month/day convenience keys. Tuple returns converted to lists.

Phase 3 — Declarative handlers: HandlerDef type, defhandler special form,
handler registry (service → name → HandlerDef), async evaluator+renderer
(async_eval.py) that awaits I/O primitives inline within control flow.
Handler loading from .sx files, execute_handler, blueprint factory.

Phase 4 — Convert all fragment routes: 13 Python fragment handlers across
8 services replaced with declarative .sx handler files. All routes.py
simplified to uniform sx dispatch pattern. Two Jinja HTML handlers
(events/container-cards, events/account-page) kept as Python.

New files: shared/sx/async_eval.py, shared/sx/handlers.py,
shared/sx/tests/test_handlers.py, plus 13 handler .sx files under
{service}/sx/handlers/. MarketService.product_by_slug() added.

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

shared/sx/primitives.py

@@ -408,6 +408,84 @@ def prim_into(target: Any, coll: Any) -> Any:
     raise ValueError(f"into: unsupported target type {type(target).__name__}")
 
 
+# ---------------------------------------------------------------------------
+# URL helpers
+# ---------------------------------------------------------------------------
+
+@register_primitive("app-url")
+def prim_app_url(service: str, path: str = "/") -> str:
+    """``(app-url "blog" "/my-post/")`` → full URL for service."""
+    from shared.infrastructure.urls import app_url
+    return app_url(service, path)
+
+
+@register_primitive("url-for")
+def prim_url_for(endpoint: str, **kwargs: Any) -> str:
+    """``(url-for "endpoint")`` → quart.url_for."""
+    from quart import url_for
+    return url_for(endpoint, **kwargs)
+
+
+@register_primitive("asset-url")
+def prim_asset_url(path: str = "") -> str:
+    """``(asset-url "/img/logo.png")`` → versioned static URL."""
+    from shared.infrastructure.urls import asset_url
+    return asset_url(path)
+
+
+@register_primitive("config")
+def prim_config(key: str) -> Any:
+    """``(config "key")`` → shared.config.config()[key]."""
+    from shared.config import config
+    cfg = config()
+    return cfg.get(key)
+
+
+@register_primitive("jinja-global")
+def prim_jinja_global(key: str, default: Any = None) -> Any:
+    """``(jinja-global "key")`` → current_app.jinja_env.globals[key]."""
+    from quart import current_app
+    return current_app.jinja_env.globals.get(key, default)
+
+
+@register_primitive("relations-from")
+def prim_relations_from(entity_type: str) -> list[dict]:
+    """``(relations-from "page")`` → list of RelationDef dicts."""
+    from shared.sx.relations import relations_from
+    return [
+        {
+            "name": d.name, "from_type": d.from_type, "to_type": d.to_type,
+            "cardinality": d.cardinality, "nav": d.nav,
+            "nav_icon": d.nav_icon, "nav_label": d.nav_label,
+        }
+        for d in relations_from(entity_type)
+    ]
+
+
+# ---------------------------------------------------------------------------
+# Format helpers
+# ---------------------------------------------------------------------------
+
+@register_primitive("format-date")
+def prim_format_date(date_str: Any, fmt: str) -> str:
+    """``(format-date date-str fmt)`` → formatted date string."""
+    from datetime import datetime
+    try:
+        dt = datetime.fromisoformat(str(date_str))
+        return dt.strftime(fmt)
+    except (ValueError, TypeError):
+        return str(date_str) if date_str else ""
+
+
+@register_primitive("parse-int")
+def prim_parse_int(val: Any, default: Any = 0) -> int | Any:
+    """``(parse-int val default?)`` → int(val) with fallback."""
+    try:
+        return int(val)
+    except (ValueError, TypeError):
+        return default
+
+
 # ---------------------------------------------------------------------------
 # Assertions
 # ---------------------------------------------------------------------------