Rebrand sexp → sx across web platform (173 files)

Rename all sexp directories, files, identifiers, and references to sx.
artdag/ excluded (separate media processing DSL).

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

cart/bp/cart/page_routes.py

@@ -5,7 +5,7 @@ from __future__ import annotations
 from quart import Blueprint, g, redirect, make_response, url_for
 
 from shared.browser.app.utils.htmx import is_htmx_request
-from shared.sexp.helpers import sexp_response
+from shared.sx.helpers import sx_response
 from shared.infrastructure.actions import call_action
 from .services import (
     total,
@@ -41,8 +41,8 @@ def register(url_prefix: str) -> Blueprint:
             ticket_total=ticket_total,
         )
 
-        from shared.sexp.page import get_template_context
-        from sexp.sexp_components import render_page_cart_page, render_page_cart_oob
+        from shared.sx.page import get_template_context
+        from sx.sx_components import render_page_cart_page, render_page_cart_oob
 
         ctx = await get_template_context()
         if not is_htmx_request():
@@ -52,11 +52,11 @@ def register(url_prefix: str) -> Blueprint:
             )
             return await make_response(html)
         else:
-            sexp_src = await render_page_cart_oob(
+            sx_src = await render_page_cart_oob(
                 ctx, post, cart, cal_entries, page_tickets,
                 ticket_groups, total, calendar_total, ticket_total,
             )
-            return sexp_response(sexp_src)
+            return sx_response(sx_src)
 
     @bp.post("/checkout/")
     async def page_checkout():
@@ -111,8 +111,8 @@ def register(url_prefix: str) -> Blueprint:
         hosted_url = result.get("sumup_hosted_url")
 
         if not hosted_url:
-            from shared.sexp.page import get_template_context
-            from sexp.sexp_components import render_checkout_error_page
+            from shared.sx.page import get_template_context
+            from sx.sx_components import render_checkout_error_page
             tctx = await get_template_context()
             html = await render_checkout_error_page(tctx, error="No hosted checkout URL returned from SumUp.")
             return await make_response(html, 500)