Fix empty code blocks: rename ~docs/code param, fix batched IO dispatch

Two bugs caused code blocks to render empty across the site:

1. ~docs/code component had parameter named `code` which collided with
   the HTML <code> tag name. Renamed to `src` and updated all 57
   callers. Added font-mono class for explicit monospace.

2. Batched IO dispatch in ocaml_bridge.py only skipped one leading
   number (batch ID) but the format has two (epoch + ID):
   (io-request EPOCH ID "name" args...). Changed to skip all leading
   numbers so the string name is correctly found. This fixes highlight
   and other batchable helpers returning empty results.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

sx/sxc/docs.sx

@@ -14,9 +14,10 @@
     (h3 :class "text-xl font-semibold text-stone-700" title)
     children))
 
-(defcomp ~docs/code (&key code)
+(defcomp ~docs/code (&key src)
   (div :class "not-prose bg-stone-100 rounded-lg p-5 mx-auto max-w-3xl"
-    (pre :class "text-sm leading-relaxed whitespace-pre-wrap break-words" (code code))))
+    (pre :class "text-sm leading-relaxed whitespace-pre-wrap break-words font-mono"
+      (code src))))
 
 (defcomp ~docs/note (&key &rest children)
   (div :class "border-l-4 border-violet-400 bg-violet-50 p-4 text-stone-700 text-sm"