Add Windows support: linker, oh-my-posh installer, README

- link-dotfiles.ps1: stow-equivalent for Windows using junctions/symlinks
  (no admin required), idempotent with .bak backups and -DryRun
- lk-installers/install-ohmyposh.ps1: winget-based install with fallback
- README.md: document Linux/macOS (stow) and Windows flows
- .gitignore: resolve leftover merge conflict markers, ignore *.bak
- ohmyposh/lkraven.toml: oh-my-posh v3 auto-migrated this on load (same
  theme, upgraded schema)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

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+# dotfiles
+
+Personal dotfiles. Configs are organized by where they get linked:
+
+| Folder         | Links into   | Examples                          |
+| -------------- | ------------ | --------------------------------- |
+| `home_root`    | `~`          | `.zshrc`, `.wezterm.lua`, `.nanorc` |
+| `home_config`  | `~/.config`  | `nvim`, `ohmyposh`, `zellij`, `ghostty` |
+| `lk-installers`| n/a          | helper scripts to install tooling |
+
+## Linux / macOS (GNU stow)
+
+Requires [`stow`](https://www.gnu.org/software/stow/).
+
+```bash
+./link-dotfiles
+```
+
+This runs `stow home_root` and `stow --target=$HOME/.config home_config`.
+
+## Windows (PowerShell)
+
+`stow` doesn't run natively on Windows, so use the PowerShell equivalent. It
+mirrors stow by creating **junctions** for directories and **symlinks/hardlinks**
+for files — none of which require administrator rights:
+
+```powershell
+pwsh -File .\link-dotfiles.ps1
+```
+
+- Re-running is safe: already-correct links are skipped.
+- Any real file/dir that would be overwritten is moved aside to `<name>.bak`.
+- Preview without changing anything: `pwsh -File .\link-dotfiles.ps1 -DryRun`
+
+The repo stays the source of truth — edit files under `home_root` /
+`home_config` and the linked locations update live.
+
+## Installers
+
+| Script                          | Platform | Purpose            |
+| ------------------------------- | -------- | ------------------ |
+| `lk-installers/install-ohmyposh`     | bash     | oh-my-posh (Linux/macOS) |
+| `lk-installers/install-ohmyposh.ps1` | pwsh     | oh-my-posh (Windows, via winget) |
+
+```powershell
+# Windows: install oh-my-posh, then link
+pwsh -File .\lk-installers\install-ohmyposh.ps1
+pwsh -File .\link-dotfiles.ps1
+```
+
+### oh-my-posh
+
+The prompt theme lives at `home_config/ohmyposh/lkraven.toml` and is loaded from
+your shell profile, e.g. in PowerShell:
+
+```powershell
+oh-my-posh init pwsh --config '~/.config/ohmyposh/lkraven.toml' | Invoke-Expression
+```
+
+It expects a Nerd Font (e.g. **VictorMono Nerd Font Mono**) to be installed and
+selected in your terminal for the glyphs to render correctly.