Dev infra: Windows-first bootstrap - portable MySQL/Redis stack, no WSL required

Adds script/bootstrap/windows/*.ps1 (PowerShell 5.1-compatible) as the primary
bootstrap path, validated end-to-end on a real Windows 10 machine:

- Portable stack under gitignored .devstack/: MySQL 8.4.11 (official
  cdn.mysql.com zip, --initialize-insecure, bound to 127.0.0.1) and Redis
  5.0.14.1 (tporadowski build, REDIS_ZIP_URL-overridable) run as plain user
  processes - no admin, no services, no WSL, no Docker
- bootstrap_dev_stack.ps1: winget-installs missing build tools (Strawberry
  Perl, NASM, LLVM; wreq's BoringSSL + aws-lc-sys need them), compiles
  diesel_cli against the portable MySQL's own client lib
  (MYSQLCLIENT_LIB_DIR), runs all 281 migrations, seeds roles/badges
  idempotently, generates the dummy secrets env (plus TEMP_DIR for Windows),
  builds storyteller-web, installs frontend deps
- start/stop_dev_services.ps1, run_backend_dev.ps1, seed_demo_user.ps1,
  dev_stack_doctor.ps1 mirror the bash variants
- Invoke-Native (cmd /c ... 2>&1) wraps long-running native calls so PS 5.1
  cannot turn harmless stderr warnings into terminating NativeCommandErrors
  when output is captured; my.ini uses forward slashes (MySQL escape rules)

Verified on this machine: 281/281 migrations applied, backend built (3m05s)
and booted on :12345 with dummy secrets, POST /v1/create_account +
/v1/login round-trip succeeded, webapp dev server served on :4201, doctor
reports 0 failures. The bash scripts remain the Linux/WSL2/CI path.

script/bootstrap/bootstrap_dev_stack.sh

@@ -2,8 +2,9 @@
 # Bootstrap the full local dev stack (backend + frontend) on a fresh clone.
 #
 # Target platform: Ubuntu 22.04+ — native, WSL2, or a CI runner/container.
-# (macOS users: follow _docs/dev_setup_server.md manually; Windows users: run
-# this inside WSL2. See _docs/dev_setup_local_stack.md.)
+# (Windows users: the native PowerShell variant in script/bootstrap/windows/
+# is the primary path — no WSL needed. macOS users: follow
+# _docs/dev_setup_server.md manually. See _docs/dev_setup_local_stack.md.)
 #
 # Idempotent: safe to re-run at any time; each step detects work already done.
 #
@@ -94,7 +95,7 @@ ensure_supported_platform() {
       die "This script targets Ubuntu/WSL2. On macOS, follow _docs/dev_setup_server.md."
       ;;
     *)
-      die "Unsupported platform '$(uname -s)'. Run inside WSL2 Ubuntu (wsl --install -d Ubuntu-22.04)."
+      die "Unsupported platform '$(uname -s)'. On Windows use script/bootstrap/windows/bootstrap_dev_stack.ps1 (native), or WSL2 Ubuntu for this script."
       ;;
   esac