fix(devcontainer): cross-platform initializeCommand + soften Windows-native posture

The previous commit's `initializeCommand` was POSIX-only (`mkdir -p $HOME/...`).
VS Code on Windows runs the host shell as `cmd.exe /c ...`, which can't
parse POSIX syntax — `$HOME` doesn't expand, `mkdir -p` errors, the init
fails with `The syntax of the command is incorrect`, and container
creation aborts before Docker is invoked.

Switch `initializeCommand` to the spec's OS-keyed object form:
- linux/darwin (covers WSL2 because VS Code runs initializeCommand in
  the WSL shell when attached via the WSL extension): POSIX mkdir+touch,
  as before
- win32: PowerShell snippet that creates the same directories under
  $USERPROFILE and touches the gitconfig if missing

Soften the README's hard "WSL2 required" framing from the previous
commit. Reality per `@devcontainers/cli read-configuration` output:
`${localEnv:HOME}` on Windows-native resolves to `C:\Users\<name>`
(VS Code falls back to USERPROFILE), so the bind mount sources are
valid Windows paths and Docker Desktop handles the translation. The
earlier `accessing specified distro mount service` failure was a
separate Docker Desktop WSL-integration issue, not a HOME-resolution
issue. Windows-native works; it's just slower with more bind-mount
permission edge cases (the husky/_/h EPERM class). The README now
explains the tradeoff and steers toward WSL2 for performance + file
watchers + permission reliability, rather than blocking Windows-native
checkouts outright.

Update the troubleshooting row to reflect the new posture.

.devcontainer/README.md

@@ -1,6 +1,6 @@
 # GitNexus Devcontainer
 
-A cross-platform Dev Container that pre-installs Claude Code, OpenAI Codex CLI, and Cursor CLI alongside the GitNexus native build chain. Supported hosts: **macOS, Linux, and Windows 11 via WSL2** (Windows-native is unsupported — see below).
+A cross-platform Dev Container that pre-installs Claude Code, OpenAI Codex CLI, and Cursor CLI alongside the GitNexus native build chain. Supported hosts: **macOS, Linux, Windows 11 via WSL2 (strongly recommended), and Windows 11 native (works but slower, with more bind-mount edge cases — see below).**
 
 ## Quick start
 
@@ -10,9 +10,15 @@ A cross-platform Dev Container that pre-installs Claude Code, OpenAI Codex CLI,
 4. Wait for the first build (~3–6 minutes) and `postCreateCommand` to finish installing workspace dependencies.
 5. Authenticate the three CLIs once — see [First-time CLI authentication](#first-time-cli-authentication) below.
 
-## Windows 11 — WSL2 is required
+## Windows 11 — WSL2 is strongly recommended
 
-**Windows-native is unsupported.** The devcontainer bind-mounts host config dirs via `${localEnv:HOME}/.claude` (and `.codex`, `.cursor`, `.gitconfig`, `.config/gh`). On Windows-native, the host has `USERPROFILE` set but no `HOME` — VS Code resolves the missing `HOME` to an empty string and Docker tries to bind-mount paths from filesystem root, which silently breaks the host-sync feature. The same checkout-from-Windows-side path also has poor IO and unreliable file watchers (Vite/jest `--watch` will miss changes). The fix is to clone and open the repo inside WSL2:
+Both WSL2 and Windows-native checkouts work. WSL2 is meaningfully better:
+
+- **File-watcher reliability.** Vite/jest `--watch` see file changes reliably on the WSL2 filesystem; Windows-native bind-mounts miss events intermittently.
+- **`npm install` performance.** WSL2-side IO is ~3-5× faster for the heavy `gitnexus` install (tree-sitter native bindings, onnxruntime, vendored grammars).
+- **No bind-mount permission edge cases.** Docker Desktop's Windows bind-mount permission translation can EPERM when a previous container created a file (e.g., `.husky/_/h`) and a new container with a different effective UID tries to overwrite it. WSL2-side filesystems don't have this class of issue (the `post-create.sh` defensive `rm -rf .husky/_` mitigates the most common case but isn't a full fix).
+
+To clone and open the repo inside WSL2:
 
 ```bash
 # 1. Install WSL2 and a Linux distro if you haven't already.
@@ -179,7 +185,7 @@ Bump `CLAUDE_CODE_VERSION` and `CODEX_VERSION` in `.devcontainer/devcontainer.js
 
 | Symptom | Likely cause | Fix |
 |---------|--------------|-----|
-| `EACCES` / `EPERM` writing into `~/.claude`, `~/.codex`, or `~/.cursor` inside the container | Windows-side bind-mount permission translation got out of sync after a UID change between rebuilds | Move to WSL2 — Windows-native isn't supported. See [Windows 11 — WSL2 is required](#windows-11--wsl2-is-required) |
+| `EACCES` / `EPERM` writing into `~/.claude`, `~/.codex`, or `~/.cursor` inside the container | Windows-side bind-mount permission translation got out of sync after a UID change between rebuilds | Move the affected dir aside and let the CLI rebuild it (`mv ~/.claude ~/.claude.bak` and log in again). Long-term: clone in WSL2 — that filesystem doesn't hit this class of issue. See [Windows 11 — WSL2 is strongly recommended](#windows-11--wsl2-is-strongly-recommended) |
 | `EPERM: operation not permitted, copyfile ... '.husky/_/h'` in `postCreateCommand` | Leftover `.husky/_/` from a previous container run on a Windows-side bind mount | `post-create.sh` already runs `rm -rf .husky/_` defensively. If you hit this on an older config, delete `.husky/_/` on the host and rebuild. Long-term: clone in WSL2 |
 | Vite never hot-reloads | Repo cloned on Windows side, not WSL2 | Re-clone inside WSL2 |
 | `gitnexus-web` can't reach the backend | `4747` was remapped or backend isn't running | Verify the Ports panel shows `4747` forwarded with no remap; start the backend with `cd gitnexus && npx gitnexus serve` |

.devcontainer/devcontainer.json

@@ -21,10 +21,17 @@
 
   // Runs on the HOST shell before the container is created. Guarantees the
   // bind-mount source directories below exist so Docker doesn't reject the
-  // mount when a CLI has never been used on this host. Idempotent; safe to
-  // re-run. POSIX-shell only (Linux / macOS / WSL2) — Windows-native is
-  // out of scope per README's WSL2-required posture.
-  "initializeCommand": "mkdir -p $HOME/.claude $HOME/.codex $HOME/.cursor $HOME/.config/gh && touch $HOME/.gitconfig",
+  // mount when a CLI has never been used on this host. OS-keyed because
+  // VS Code runs the host shell in its native form (POSIX on Linux/macOS,
+  // cmd.exe on Windows — which means `mkdir -p` + `$HOME` won't work on
+  // Win32). All three branches are idempotent. WSL is covered by the
+  // linux branch because VS Code's WSL extension runs initializeCommand
+  // in the WSL shell.
+  "initializeCommand": {
+    "linux": "mkdir -p $HOME/.claude $HOME/.codex $HOME/.cursor $HOME/.config/gh && touch $HOME/.gitconfig",
+    "darwin": "mkdir -p $HOME/.claude $HOME/.codex $HOME/.cursor $HOME/.config/gh && touch $HOME/.gitconfig",
+    "win32": "powershell -NoProfile -Command \"$d=$env:USERPROFILE; foreach ($p in '.claude','.codex','.cursor','.config\\gh') { $f=Join-Path $d $p; if (-not (Test-Path $f)) { New-Item -ItemType Directory -Force -Path $f | Out-Null } }; if (-not (Test-Path (Join-Path $d '.gitconfig'))) { New-Item -ItemType File -Path (Join-Path $d '.gitconfig') | Out-Null }\""
+  },
 
   "features": {
     "ghcr.io/devcontainers/features/github-cli:1": {}