host: SX-native wire — reads + write bodies are text/sx, JSON CRUD deleted

Greenfield SX-native pivot (NOT a strangler): the host speaks SX/SXTP end to end;
JSON only at the future ActivityPub federation edge.

- OUTPUT: host/json-status -> host/sx-status — every host/ok/host/error response is
  text/sx via the serialize primitive (NOT application/json). Flips feed, relations,
  blog reads. Tests assert the SX envelope ({:ok true :data ...}).
- DELETE the blog JSON CRUD /posts (POST/PUT/DELETE) + bearer-based host/blog--protect:
  a pure old-contract REST mirror. Create/edit go through the HTML editor forms;
  programmatic writes speak SXTP. FOLLOW-UP: no browser delete route yet (was JSON-only,
  no UI) — add POST /:slug/delete + cascade edge cleanup when the metamodel UI needs it.
- INPUT: host/sx-body (sxtp.sx) parses a text/sx request body to a string-keyed dict
  (parse-safe + sxtp/-normalize). feed POST + relations attach/detach read it.
- UNIFIED field reader host/fields / host/field: text/sx body OR urlencoded form by
  content-type. The blog form handlers (new/edit/relate/unrelate) + login read through
  it — additive, urlencoded still works (no-engine / bootstrap fallback).

Conformance 290/290 (11 suites). Retires the strangler framing in the plan; adds the
'SX all the way out' wire table. The engine half (browser posts text/sx) follows.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/host/tests/relations.sx

@@ -88,19 +88,11 @@
 (host-rl-test
   "golden children"
   (dream-resp-body (host-rl-app (host-rl-req host-rl-kids)))
-  (str
-    "{\"ok\":true,\"data\":"
-    (dream-json-encode
-      (host/-rel-strings (relations/children (host-rl-sym "org:1") (host-rl-sym "member"))))
-    "}"))
+  (serialize {:ok true :data (host/-rel-strings (relations/children (host-rl-sym "org:1") (host-rl-sym "member")))}))
 (host-rl-test
   "golden parents"
   (dream-resp-body (host-rl-app (host-rl-req host-rl-par)))
-  (str
-    "{\"ok\":true,\"data\":"
-    (dream-json-encode
-      (host/-rel-strings (relations/parents (host-rl-sym "list:7") (host-rl-sym "member"))))
-    "}"))
+  (serialize {:ok true :data (host/-rel-strings (relations/parents (host-rl-sym "list:7") (host-rl-sym "member")))}))
 
 ;; ── writes: attach-child / detach-child (auth + ACL + closed loop) ──
 (acl/load!
@@ -119,7 +111,7 @@
     (dream-request "POST" (str "/internal/actions/" action)
       (if auth {:authorization auth} {}) body)))
 (define host-rl-edge
-  "{\"parent-type\":\"org\",\"parent-id\":\"2\",\"child-type\":\"list\",\"child-id\":\"5\",\"relation-type\":\"member\"}")
+  "{:parent-type \"org\" :parent-id \"2\" :child-type \"list\" :child-id \"5\" :relation-type \"member\"}")
 (define host-rl-org2
   "/internal/data/get-children?parent-type=org&parent-id=2&relation-type=member")
 
@@ -162,12 +154,12 @@
 ;; bad payloads
 (host-rl-test
   "attach non-object body -> 400"
-  (dream-status (host-rl-wapp (host-rl-post "attach-child" "Bearer good" "[1,2]")))
+  (dream-status (host-rl-wapp (host-rl-post "attach-child" "Bearer good" "(1 2)")))
   400)
 (host-rl-test
   "attach missing param -> 400"
   (dream-status
-    (host-rl-wapp (host-rl-post "attach-child" "Bearer good" "{\"parent-type\":\"org\"}")))
+    (host-rl-wapp (host-rl-post "attach-child" "Bearer good" "{:parent-type \"org\"}")))
   400)
 
 (define