fix(windows): sweep remaining unguarded text-mode subprocess sites codebase-wide

AST-driven pass over every subprocess.run/Popen/check_output/check_call/call
with text=True (or universal_newlines=True) and no explicit encoding=:
append encoding='utf-8', errors='replace' at the kwarg site. 136 call
sites across 28 files (cli.py, hermes_cli/main.py, tools_config.py,
environments, computer_use, gateway, scripts, skills helpers, agent/*).

Together with the salvaged #55339/#60741 commits this closes out issue
#53428's bug class; the salvaged #60751 linter rule in
check-windows-footguns.py now enforces it repo-wide (verified: 807 files
scanned, zero findings).

scripts/ci/lockfile_diff.py

@@ -115,7 +115,7 @@ def _git_show(ref: str, path: str, repo_root: str) -> str | None:
     proc = subprocess.run(
         ["git", "show", f"{ref}:{path}"],
         capture_output=True,
-        text=True,
+        text=True, encoding="utf-8", errors="replace",
         cwd=repo_root,
     )
     return proc.stdout if proc.returncode == 0 else None
@@ -125,7 +125,7 @@ def _tracked_lockfiles(ref: str, repo_root: str) -> set[str]:
     proc = subprocess.run(
         ["git", "ls-tree", "-r", "--name-only", ref],
         capture_output=True,
-        text=True,
+        text=True, encoding="utf-8", errors="replace",
         cwd=repo_root,
         check=True,
     )