kernel+bundle: fix nil-bytecode .sxbc (compile-blob serializer dropped Integer)

Every .sxbc shipped with `:bytecode (nil nil ...)` and `:arity nil`, so the WASM
kernel's vm.sx hit "VM: unknown opcode 0" on every module and fell back to .sx
source (slower, noisy console). Root cause: `raw_serialize` in the `compile-blob`
command (sx_server.ml) handles `Number` but not `Integer`, and bytecode opcodes +
arity/upvalue-count are `Integer`s — so they fell through to the `_ -> "nil"`
catch-all and serialized as nil. Same class of bug as the value_to_js Integer gap
(689dae7d). It went unnoticed because source-fallback masks it. Add the Integer
case and regenerate: the web stack now loads entirely from bytecode (0 unknown-
opcode warnings, 0 source fallbacks), boost + SPA unchanged. compiler.sx in the
bundle was also stale — re-synced to the canonical lib/compiler.sx.

Verified: native host conformance 271/271; chromium boots with 0 unknown-opcode
warnings + 0 source-fallback loads; spa-check still passes (boost 6/6, fragment
swap). Prereq for content-addressing the assets (caching real bytecode, not nil).

hosts/ocaml/bin/sx_server.ml

@@ -1790,6 +1790,10 @@ let rec dispatch env cmd =
         | Nil -> "nil"
         | Bool true -> "true" | Bool false -> "false"
         | Number n -> Sx_types.format_number n
+        (* Bytecode opcodes + arity/upvalue-count are Integers; without this case
+           they hit the `_ -> "nil"` fallthrough, so every .sxbc came out as
+           `:bytecode (nil nil ...)` -> "VM: unknown opcode 0" -> source fallback. *)
+        | Integer n -> string_of_int n
         | String s -> "\"" ^ escape_sx_string s ^ "\""
         | Symbol s -> s | Keyword k -> ":" ^ k
         | List items | ListRef { contents = items } -> "(" ^ String.concat " " (List.map raw_serialize items) ^ ")"