G-102: build.zig entry shim; deterministic critcl target; zig pin in comptime gate

Three deltas surfaced by the PATH-scrubbed clean-checkout demonstration:

- build.zig: default-entry re-export of build905.zig's build so the documented
  plain 'zig build stage|bootstrap' works from the tracked suite dir (the
  recipe keeps its versioned filename; staged flows still invoke it via
  --build-file).
- critcl_zig.config + recipe: settings move under an EXPLICIT target
  (win32-x86_64-zig) and the tcllibc step passes -target win32-x86_64-zig.
  critcl otherwise chooses its build target by probing PATH for compilers -
  with a gcc visible the config defaults engaged (why G-098's flow worked),
  but the scrubbed environment fell back to critcl's builtin msvc 'cl'
  target and all 25 accelerator modules failed with "couldn't execute cl".
  Verified green in BOTH environments (scrubbed and normal PATH).
- build905.zig comptime gate: the stale 0.13-dev minimum becomes the actual
  suite pin (0.16.0) with a message pointing at punk-getzig and the README
  (acceptance: the recipe records the zig version it is written against).

Assisted-by: harness=claude; primary-model=claude-fable-5; api-location=anthropic.com

src/buildsuites/suite_tcl90/build.zig

@@ -0,0 +1,7 @@
+//build.zig - default-entry shim so plain 'zig build <step>' works from this
+//directory (the bootstrap-flow invocations in the README). The recipe itself
+//lives in build905.zig - a deliberately VERSIONED name (the staged flows invoke
+//it explicitly via --build-file, and a future suite may carry more than one
+//recipe file). build.zig.zon beside this file serves both entry points.
+const recipe = @import("build905.zig");
+pub const build = recipe.build;

src/buildsuites/suite_tcl90/build905.zig

@@ -44,20 +44,17 @@ var static_build: bool = true;
 //}
 
 comptime {
-    //const required_zig = "0.14.0-dev.300";
-    const required_zig = "0.13.0-dev.8";
+    //The suite pin (G-102 acceptance: the recipe records the zig version it is
+    //written against). The recipe is 0.16-API and does not build under 0.14/0.15;
+    //punk-getzig materializes the pinned toolchain (see README Pinned zig).
+    const required_zig = "0.16.0";
     const current_zig = builtin.zig_version;
     const min_zig = std.SemanticVersion.parse(required_zig) catch unreachable;
     if (current_zig.order(min_zig) == .lt) {
         const error_message =
-            \\Sorry, it looks like your version of zig is too old. :-(
-            \\
-            \\punk tcl requires development build {}
-            \\
-            \\Please download a development ("master") build from
-            \\
-            \\https://ziglang.org/download/
-            \\
+            \\This recipe is written against zig {} (see README Pinned zig) and
+            \\does not build with older zigs. bin/punk-getzig fetches the pinned
+            \\toolchain; https://ziglang.org/download/ hosts releases.
             \\
         ;
         @compileError(std.fmt.comptimePrint(error_message, .{min_zig}));
@@ -2298,6 +2295,11 @@ pub fn build(b: *std.Build) !void {
         critcl_run.addFileArg(b.path("../critcl/main.tcl"));
         critcl_run.addArg("-config");
         critcl_run.addFileArg(b.path("critcl_zig.config"));
+        //pin the build target to the config's explicit section: critcl otherwise
+        //GUESSES its target by probing PATH for compilers - with a gcc visible the
+        //config defaults engaged, but a scrubbed environment fell back to critcl's
+        //builtin msvc 'cl' target and never used the zig cc settings (G-102 finding).
+        critcl_run.addArgs(&.{ "-target", "win32-x86_64-zig" });
         critcl_run.addArg("-cache");
         _ = critcl_run.addOutputDirectoryArg("critcl-cache");
         critcl_run.addArg("-force");

src/buildsuites/suite_tcl90/critcl_zig.config

@@ -1,25 +1,34 @@
-# suite_tcl90 critcl configuration: zig cc as the C toolchain (G-098).
-# Overrides critcl's gcc-style defaults; 'zig' is resolved from PATH - the suite
-# driver prepends the pinned bin/tools zig dir for the critcl invocation.
-# Target is the native windows-gnu triple (matches the suite's tcl runtime ABI).
+# suite_tcl90 critcl configuration: zig cc as the C toolchain (G-098, G-102).
+# 'zig' is resolved from PATH - the suite recipe prepends the pinned bin/tools zig
+# dir for the critcl invocation. Target is the native windows-gnu triple (matches
+# the suite's tcl runtime ABI).
+#
+# The settings live under an EXPLICIT target, win32-x86_64-zig, and the recipe
+# invokes critcl with '-target win32-x86_64-zig': critcl otherwise chooses its
+# build target by PROBING the environment for compilers, which made the selection
+# depend on what happened to be on PATH (a visible gcc landed on the config
+# defaults; a scrubbed environment fell back to critcl's builtin msvc 'cl'
+# target and never used these settings - G-102 finding).
 
 platform        win32-x86_64
-compile         zig cc -target x86_64-windows-gnu -c -fPIC
-version         zig version
-link            zig cc -target x86_64-windows-gnu -shared
-include         -I
-libinclude      -L
-object          .o
-output          -o [list $outfile]
-optimize        -O2
-noassert        -DNDEBUG
-tclstubs        -DUSE_TCL_STUBS
-tkstubs         -DUSE_TK_STUBS
-debug_symbols   -g
-strip           -Wl,-s
-link_debug
-link_release
-embed_manifest
-ldoutput
-link_preload
-sharedlibext    .dll
+
+win32-x86_64-zig  platform        win32-x86_64
+win32-x86_64-zig  compile         zig cc -target x86_64-windows-gnu -c -fPIC
+win32-x86_64-zig  version         zig version
+win32-x86_64-zig  link            zig cc -target x86_64-windows-gnu -shared
+win32-x86_64-zig  include         -I
+win32-x86_64-zig  libinclude      -L
+win32-x86_64-zig  object          .o
+win32-x86_64-zig  output          -o [list $outfile]
+win32-x86_64-zig  optimize        -O2
+win32-x86_64-zig  noassert        -DNDEBUG
+win32-x86_64-zig  tclstubs        -DUSE_TCL_STUBS
+win32-x86_64-zig  tkstubs         -DUSE_TK_STUBS
+win32-x86_64-zig  debug_symbols   -g
+win32-x86_64-zig  strip           -Wl,-s
+win32-x86_64-zig  link_debug
+win32-x86_64-zig  link_release
+win32-x86_64-zig  embed_manifest
+win32-x86_64-zig  ldoutput
+win32-x86_64-zig  link_preload
+win32-x86_64-zig  sharedlibext    .dll