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>

shared/browser/app/errors.py

@@ -57,9 +57,9 @@ def _error_page(message: str) -> str:
     )
 
 
-def _sexp_error_page(errnum: str, message: str, image: str | None = None) -> str:
+def _sx_error_page(errnum: str, message: str, image: str | None = None) -> str:
     """Render an error page via s-expressions. Bypasses Jinja entirely."""
-    from shared.sexp.page import render_page
+    from shared.sx.page import render_page
 
     return render_page(
         '(~error-page :title title :message message :image image :asset-url "/static")',
@@ -147,24 +147,24 @@ async def _rich_error_page(errnum: str, message: str, image: str | None = None)
                 pass
 
         # Root header (site nav bar)
-        from shared.sexp.helpers import (
-            root_header_sexp, post_header_sexp,
-            header_child_sexp, full_page_sexp, sexp_call,
+        from shared.sx.helpers import (
+            root_header_sx, post_header_sx,
+            header_child_sx, full_page_sx, sx_call,
         )
-        hdr = root_header_sexp(ctx)
+        hdr = root_header_sx(ctx)
 
         # Post breadcrumb if we resolved a post
         post = (post_data or {}).get("post") or ctx.get("post") or {}
         if post.get("slug"):
             ctx["post"] = post
-            post_row = post_header_sexp(ctx)
+            post_row = post_header_sx(ctx)
             if post_row:
-                hdr = "(<> " + hdr + " " + header_child_sexp(post_row) + ")"
+                hdr = "(<> " + hdr + " " + header_child_sx(post_row) + ")"
 
         # Error content
-        error_content = sexp_call("error-content", errnum=errnum, message=message, image=image)
+        error_content = sx_call("error-content", errnum=errnum, message=message, image=image)
 
-        return full_page_sexp(ctx, header_rows=hdr, content=error_content)
+        return full_page_sx(ctx, header_rows=hdr, content=error_content)
     except Exception:
         current_app.logger.debug("Rich error page failed, falling back", exc_info=True)
         return None
@@ -202,7 +202,7 @@ def errors(app):
             )
             if html is None:
                 try:
-                    html = _sexp_error_page(
+                    html = _sx_error_page(
                         "404", "NOT FOUND",
                         image="/static/errors/404.gif",
                     )
@@ -224,7 +224,7 @@ def errors(app):
             )
         else:
             try:
-                html = _sexp_error_page(
+                html = _sx_error_page(
                     "403", "FORBIDDEN",
                     image="/static/errors/403.gif",
                 )
@@ -244,7 +244,7 @@ def errors(app):
         messages = getattr(e, "messages", [str(e)])
 
         if request.headers.get("SX-Request") == "true" or request.headers.get("HX-Request") == "true":
-            from shared.sexp.jinja_bridge import render as render_comp
+            from shared.sx.jinja_bridge import render as render_comp
             items = "".join(
                 render_comp("error-list-item", message=str(escape(m)))
                 for m in messages if m
@@ -266,7 +266,7 @@ def errors(app):
         # Extract service name from "Fragment account/auth-menu failed: ..."
         service = msg.split("/")[0].replace("Fragment ", "") if "/" in msg else "unknown"
         if request.headers.get("SX-Request") == "true" or request.headers.get("HX-Request") == "true":
-            from shared.sexp.jinja_bridge import render as render_comp
+            from shared.sx.jinja_bridge import render as render_comp
             return await make_response(
                 render_comp("fragment-error", service=str(escape(service))),
                 503,