docs(windows): expand windows.md with kernel bootstrap, env inheritance, lock cleanup

[abdulazizFarhan]

Expands packages/coding-agent/docs/windows.md with the IPython kernel bootstrap workflow for Windows.

Added sections:

• One-shot Python kernel provisioning (PowerShell + Git Bash variants). Lists all 13 required packages — with tyro and dill called out as the easy ones to miss (Prime Agent's bootstrap only reports the first missing group per run).
• PowerShell user-level env var inheritance quirk. setx writes a user-level var, but PowerShell does NOT auto-inherit user-level vars into the process env (cmd does). The wrapper must explicitly copy them via [System.Environment]::SetEnvironmentVariable($name, $value, 'Process'). This is the most common silent failure for PowerShell-launched prime-agent sessions.
• Stale session-leases/*.lock cleanup. proper-lockfile uses directories as locks on Windows. If the previous prime-agent was killed, the .lock directory blocks the next resume with EPERM: rename *.lock.candidate-XXX → *.lock. Wrapper should clear locks whose owner.json PID is no longer running.
• Failure-mode diagnosis checklist for the four common 'kernel broken' symptoms (POSIX-only bootstrap path, missing package, stale lock, bootstrap-version drift).

Why docs-only: the kernel path fix itself is already in PR #825 (fix/windows-console-flicker). This PR makes the existing workaround discoverable and documents the PowerShell + lock gotchas that bit me during setup. Closes the documentation gap for #660.

Note

Expand Windows documentation with kernel bootstrap, env inheritance, and lock cleanup

Adds several new sections to windows.md covering the full Windows setup and troubleshooting workflow:

• Documents the Python kernel bootstrap: per-user uv-managed venv location, required packages, and one-shot provisioning commands for PowerShell and Git Bash
• Adds a PowerShell snippet to import user-level environment variables before launching prime-agent, addressing env inheritance gaps on Windows
• Provides a PowerShell script to clean up stale session-lease *.lock directories whose owning PID no longer exists
• Adds a failure-mode diagnosis section covering POSIX-only path bugs, missing packages under a custom Python override, stale lock rename errors, and out-of-sync .bootstrap-version

^{Macroscope summarized f366c91.}

[kevinjosethomas]

Hi, thanks for taking the time to contribute to Prime Agent! Since open sourcing the project, we’ve received far more pull requests than we can responsibly review and validate. Prime Agent runs directly on users’ machines, so we need to be deliberate about which changes we accept and how they are reviewed. Rather than leave a large backlog that we cannot meaningfully work through, we’re closing the current PR queue and moving to a discussion-first contribution process.

We have established new contribution guidelines to help us continue iterating on Prime Agent and better manage contributions from the community. Going forward, we won’t review unsolicited pull requests. Instead, please start with a GitHub Discussion. We’ll identify recurring bugs and feature requests, create Issues for work we want to pursue, and invite pull requests from maintainers or vouched contributors when implementation is ready. Please read the full process documented in our contribution guidelines.

While we’re closing this backlog, we’re still reviewing it at a high level to identify recurring bugs, useful ideas, and important problems that we should address ourselves. Thanks again for the time you put into this!