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.

CLAUDE.md

@@ -576,8 +576,8 @@ Wiring a new bundling step:
 | `implementation_plan.md` | Archive of completed work (closures, protocols, etc.). Do not pick up tasks from here. |
 | `readme.md` | User-facing language overview — **maintained**. Update it whenever a user-facing sx change lands (new/changed syntax, semantics, gating diagnostics, language behavior), per the docs-track-changes rule. |
 | `CLAUDE.md` | This file. Session instructions. |
-| `library/modules/std.sx` | The prelude (print/format/List/string ops/Context/Allocator) + the namespace tail (`mem`/`xml`/`log` carried to flat importers). |
-| `library/modules/std/` | Stdlib modules: mem (allocators), fs, process, socket, json, cli, hash, xml, log, trace, test. Import directly until they join the tail. |
+| `library/modules/std.sx` | The prelude (print/format/List/string ops/Context/Allocator) + the namespace tail (`mem`/`xml`/`log`/`fs`/`process`/`socket`/`json`/`cli`/`hash`/`test` carried to flat importers). |
+| `library/modules/std/` | Stdlib modules: mem (allocators), fs, process, socket, json, cli, hash, xml, log, trace, test — all but trace carried by the std.sx tail; direct file imports give bare access. |
 | `library/modules/ffi/` | FFI bindings: objc, objc_block, sdl3, opengl, raylib, stb, stb_truetype, wasm. |
 | `library/modules/math/` | scalar / vector2 / matrix44 — one spelling: `#import "modules/math"` (directory import). |
 | `library/modules/build.sx` | `BuildOptions` compile-time build DSL. See "Bundling lives in sx" above. |