Convert social and federation profile from Jinja to SX rendering

Add primitives (replace, strip-tags, slice, csrf-token), convert all
social blueprint routes and federation profile to SX content builders,
delete 12 unused Jinja templates and social_lite layout.

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

shared/sx/primitives_io.py

@@ -41,6 +41,7 @@ IO_PRIMITIVES: frozenset[str] = frozenset({
     "nav-tree",
     "get-children",
     "g",
+    "csrf-token",
 })
 
 
@@ -314,6 +315,17 @@ async def _io_g(
     return getattr(g, key, None)
 
 
+async def _io_csrf_token(
+    args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
+) -> str:
+    """``(csrf-token)`` → current CSRF token string."""
+    from quart import current_app
+    csrf = current_app.jinja_env.globals.get("csrf_token")
+    if callable(csrf):
+        return csrf()
+    return ""
+
+
 _IO_HANDLERS: dict[str, Any] = {
     "frag": _io_frag,
     "query": _io_query,
@@ -326,4 +338,5 @@ _IO_HANDLERS: dict[str, Any] = {
     "nav-tree": _io_nav_tree,
     "get-children": _io_get_children,
     "g": _io_g,
+    "csrf-token": _io_csrf_token,
 }