Replace JSON sx-headers with SX dict expressions, fix blog like component

sx-headers attributes now use native SX dict format {:key val} instead of
JSON strings. Eliminates manual JSON string construction in both .sx files
and Python callers.

- sx.js: parse sx-headers/sx-vals as SX dict ({: prefix) with JSON fallback,
  add _serializeDict for dict→attribute serialization, fix verbInfo scope in
  _doFetch error handler
- html.py: serialize dict attribute values via SX serialize() not str()
- All .sx files: {:X-CSRFToken csrf} replaces (str "{\"X-CSRFToken\": ...}")
- All Python callers: {"X-CSRFToken": csrf} dict replaces f-string JSON
- Blog like: extract ~blog-like-toggle, fix POST returning wrong component,
  fix emoji escapes in .sx (parser has no \U support), fix card :hx-headers
  keyword mismatch, wrap sx_content in SxExpr for evaluation

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

events/sxc/pages/tickets.py

@@ -419,7 +419,7 @@ def render_ticket_types_table(ticket_types, entry, calendar, day, month, year) -
                                 tt_name=tt.name, cost_str=cost_str,
                                 count=str(tt.count), action_btn=action_btn,
                                 del_url=del_url,
-                                csrf_hdr=f'{{"X-CSRFToken": "{csrf}"}}')
+                                csrf_hdr={"X-CSRFToken": csrf})
     else:
         rows_html = sx_call("events-ticket-types-empty-row")
 
@@ -699,7 +699,7 @@ def render_ticket_type_add_form(entry, calendar, day, month, year) -> str:
     cancel_url = url_for("calendar.day.calendar_entries.calendar_entry.ticket_types.add_button",
                           calendar_slug=cal_slug, entry_id=entry.id,
                           year=year, month=month, day=day)
-    csrf_hdr = f'{{"X-CSRFToken": "{csrf}"}}'
+    csrf_hdr = {"X-CSRFToken": csrf}
 
     return sx_call("events-ticket-type-add-form",
                   post_url=post_url, csrf=csrf_hdr,