fix: Windows E2E — PowerShell copy for cp_bmi, USERPROFILE fallback, tag fixes

- cp_bmi rule: use PowerShell Copy-Item instead of cmd /c copy
  (handles forward-slash paths from ninja correctly)
- _inherit_toolchain.sh: try USERPROFILE when HOME/.mcpp doesn't exist
- 38_self_config_mirror: tag unix-shell (xlings mirror broken on Windows)
- Remove continue-on-error from E2E (real failures should block CI)

Author: Sunrisepeak

.github/workflows/ci-windows.yml

@@ -99,7 +99,6 @@ jobs:
       # Enable once available.
 
       - name: E2E suite
-        continue-on-error: true
         shell: bash
         run: |
           export MCPP="$MCPP_SELF"

src/build/ninja_backend.cppm

@@ -198,7 +198,9 @@ std::string emit_ninja_string(const BuildPlan& plan) {
 
     append("rule cp_bmi\n");
 #if defined(_WIN32)
-    append("  command = cmd /c copy /y $in $out >nul\n");
+    // Use PowerShell Copy-Item which handles both forward and back slashes.
+    // cmd.exe `copy` breaks on forward-slash paths from ninja.
+    append("  command = powershell -NoProfile -Command \"Copy-Item -Force '$in' -Destination '$out'\"\n");
 #else
     append("  command = mkdir -p $$(dirname $out) && cp -f $in $out\n");
 #endif

tests/e2e/38_self_config_mirror.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# requires:
+# requires: unix-shell
 # 38_self_config_mirror.sh — configure xlings mirror through mcpp self config.
 set -e
 

tests/e2e/_inherit_toolchain.sh

@@ -13,7 +13,11 @@ if [[ -z "${MCPP_HOME:-}" ]]; then
 fi
 mkdir -p "$MCPP_HOME"
 
+# On Windows, HOME may differ from USERPROFILE; try both
 USER_MCPP="${HOME}/.mcpp"
+if [[ ! -d "$USER_MCPP" && -n "${USERPROFILE:-}" ]]; then
+    USER_MCPP="$USERPROFILE/.mcpp"
+fi
 if [[ -d "$USER_MCPP/registry/data/xpkgs" ]]; then
     mkdir -p "$MCPP_HOME/registry/data"
     [[ -e "$MCPP_HOME/registry/data/xpkgs" ]] \