feat: add PowerShell installer for Windows

[Tourniercy]

Summary

• Add install.ps1 PowerShell installer for Windows, mirroring install.sh (arch detection, latest release download, PATH setup)
• Update README with Windows quick install one-liner: irm .../install.ps1 | iex

Test plan

• Run irm .../install.ps1 | iex on a clean Windows machine
• Verify rtk.exe lands in %USERPROFILE%\.local\bin
• Verify PATH prompt works (accept and decline)
• Verify rtk --version after install
• Test $env:RTK_INSTALL_DIR override

[FlorianBruniaux]

Hi @Tourniercy! Could you rebase on the latest master? PR #241 just merged. Your PowerShell installer PR is a good addition and we want to get it moving.

[Tourniercy]

Hi @FlorianBruniaux, my branch is now updated.

[pszymkowiak]

LGTM — clean PowerShell installer, good error handling, arch detection, PATH setup.

Before merge:

1. Rebase on master — README was revamped in docs: revamp README with logo, badges, and structure cleanup #371, your README changes will conflict. Adapt to the new README structure
2. The install.ps1 script itself looks ready

Once rebased, ready to merge.

[Tourniercy]

Done @pszymkowiak

[CLAassistant]

All committers have signed the CLA.

[Tourniercy]

@FlorianBruniaux @pszymkowiak PR is ready to merge

[pszymkowiak]

Hi! Two things needed before we can review:

1. Retarget to develop — this PR targets master, but all PRs should target develop. You can change the base branch in the PR settings (right sidebar).
2. Sign the CLA — if not already done, please sign at https://cla-assistant.io/rtk-ai/rtk

Thanks!

[aeppling]

Hey

We are cleaning up the codebase and improving the project structure for better onboarding. As part of this effort, PR #826 reorganizes src/ from a flat layout into subfolders.

No logic changes — only file moves and import path updates.

What you need to do

Rebase your branch on develop when receiving this comment:

git fetch origin && git rebase origin/develop

Git detects renames automatically. If you get import conflicts, update the paths:

use crate::git;        // now: use crate::cmds::git::git;
use crate::tracking;   // now: use crate::core::tracking;
use crate::config;     // now: use crate::core::config;
use crate::init;       // now: use crate::hooks::init;
use crate::gain;       // now: use crate::analytics::gain;

Need help rebasing? Tag @aeppling

[Tourniercy]

Done @pszymkowiak @aeppling