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.

src/ir/emit_llvm.zig

@@ -860,7 +860,27 @@ pub const LLVMEmitter = struct {
     }
 
     fn emitGlobals(self: *LLVMEmitter) void {
+        // Dead-global elimination: a plain-data global no instruction
+        // references is not emitted — without this, every module pulled in
+        // via the std namespace tail lands its data (hash's K table, ...)
+        // in every binary. Comptime-backed globals are kept: their #run
+        // evaluation (and its failure diagnostics) is a semantic effect,
+        // not just data.
+        var used = std.AutoHashMap(u32, void).init(self.alloc);
+        defer used.deinit();
+        for (self.ir_mod.functions.items) |*func| {
+            for (func.blocks.items) |*block| {
+                for (block.insts.items) |*instruction| {
+                    switch (instruction.op) {
+                        .global_get, .global_addr => |gid| used.put(gid.index(), {}) catch {},
+                        .global_set => |gs| used.put(gs.global.index(), {}) catch {},
+                        else => {},
+                    }
+                }
+            }
+        }
         for (self.ir_mod.globals.items, 0..) |global, i| {
+            if (global.comptime_func == null and !used.contains(@intCast(i))) continue;
             const name = self.ir_mod.types.getString(global.name);
             const llvm_ty = self.toLLVMType(global.ty);
             const name_z = self.alloc.dupeZ(u8, name) catch continue;