std: full namespace tail — fs/process/socket/json/cli/hash/test

With 0115's own-wins globals landed, the remaining tail modules join
std.sx: every '#import "modules/std.sx"' now carries mem/xml/log/fs/
process/socket/json/cli/hash/test as namespaces (trace stays a direct
import).

Enablers in the same change:
- emit: dead-global elimination — a plain-data global no instruction
  references is not emitted, so tail modules' data (hash's 64-entry K
  table, OS/ARCH/POINTER_SIZE) stays out of binaries that don't use it.
  Comptime-backed globals keep their #run evaluation. 37 pinned IR
  snapshots regenerated (dead globals dropped + string renumbering from
  the larger module).
- 1055/1056 stop pinning the global error-tag ordinal (it shifts with
  program composition); they assert nonzero + tag identity + name.
- specs/readme/CLAUDE.md tail docs updated.

examples/1055-errors-enum-value-failable-error-slot.sx

@@ -36,7 +36,7 @@ main :: () -> s32 {
 
     // ── error path: the right tag flows through ──
     c3, e3 := pick("xxx");
-    print("error err int = {}\n", cast(s64) e3);              // 1
+    print("error err nonzero = {}\n", cast(s64) e3 != 0);     // true (ordinal is program-global, not pinned)
     if e3 == error.Nope { print("error: is Nope (ok)\n"); } else { print("error: not Nope (WRONG)\n"); }
     print("error tag name = {}\n", error_tag_name(e3));       // Nope