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>

federation/sx/handlers/link-card.sx

@@ -0,0 +1,40 @@
+;; Federation link-card fragment handler
+;;
+;; Renders actor profile preview card(s) by username.
+;; Supports single mode (?slug=x or ?username=x) and batch mode (?keys=x,y,z).
+
+(defhandler link-card (&key username slug keys)
+  (if keys
+    (let ((usernames (filter (fn (u) (not (empty? u)))
+                      (map trim (split keys ",")))))
+      (<> (map (fn (u)
+        (let ((actor (service "federation" "get-actor-by-username" :username u)))
+          (<> (str "<!-- fragment:" u " -->")
+              (when (not (nil? actor))
+                (~link-card
+                  :link (app-url "federation"
+                          (str "/users/" (get actor "preferred_username")))
+                  :title (or (get actor "display_name")
+                             (get actor "preferred_username"))
+                  :image nil
+                  :icon "fas fa-user"
+                  :subtitle (when (get actor "preferred_username")
+                              (str "@" (get actor "preferred_username")))
+                  :detail (get actor "summary")
+                  :data-app "federation"))))) usernames)))
+    (let ((lookup (or username slug)))
+      (when (not (empty? (or lookup "")))
+        (let ((actor (service "federation" "get-actor-by-username"
+                       :username lookup)))
+          (when (not (nil? actor))
+            (~link-card
+              :link (app-url "federation"
+                      (str "/users/" (get actor "preferred_username")))
+              :title (or (get actor "display_name")
+                         (get actor "preferred_username"))
+              :image nil
+              :icon "fas fa-user"
+              :subtitle (when (get actor "preferred_username")
+                          (str "@" (get actor "preferred_username")))
+              :detail (get actor "summary")
+              :data-app "federation")))))))

federation/sx/sx_components.py

@@ -17,8 +17,9 @@ from shared.sx.helpers import (
     root_header_sx, full_page_sx, header_child_sx,
 )
 
-# Load federation-specific .sx components at import time
-load_service_components(os.path.dirname(os.path.dirname(__file__)))
+# Load federation-specific .sx components + handlers at import time
+load_service_components(os.path.dirname(os.path.dirname(__file__)),
+                        service_name="federation")
 
 
 # ---------------------------------------------------------------------------