[Bug]: loopx connect prints POSIX-only install/repair commands on native Windows #6121

Issue origin: Observed or reproduced in a real environment (native Windows).

Problem

loopx connect (bootstrap) prints repair guidance that cannot run on native Windows. The "Install / Update Hint" and "Archive Fallback" blocks are hardcoded POSIX strings:

• python3 -m pip install --upgrade loopx
• curl -fsSL https://loopx-project.github.io/loopx/install.sh | bash
• export PATH="$HOME/.local/bin:$PATH"

Native Windows hosts have no python3 launcher and no Bash, so an operator who follows the first repair instruction the CLI prints is led to commands that fail. On the same host, loopx doctor already prints the platform-correct form (the current interpreter and scripts/install-windows.ps1), so the two surfaces disagree.

Minimal reproduction

1. On a native Windows host, run the source checkout (uv sync --extra test).
2. loopx connect --project <empty-dir> --dry-run --no-global-sync
3. Read the "Install / Update Hint" and "Archive Fallback" blocks.

Version: commit ecffa78
Host: Codex CLI (native Windows)
Area: Build, packaging, installer, or CI

Expected behavior

The repair and fallback commands printed to the operator should be runnable on the host that prints them, matching the platform rule loopx doctor already applies.

Actual behavior

Both blocks always print the POSIX-only python3 / curl | bash / export PATH form, even on native Windows.

Diagnostics

None; no private state or local paths required.