install.ps1: a failed install leaves ~300 MB of orphaned jdk/ in the target directory

[fupelaqu]

Found reviewing PR #232 (Windows JDK bootstrap). Verified against install.ps1 as merged.

What happens

The JDK is bootstrapped into $Target before anything validates that the requested install can succeed:

• install.ps1:426 — if (-not (Resolve-Java)) { exit 1 }, which downloads and unpacks ~300 MB into <Target>\jdk when the host has no suitable Java
• install.ps1:1149 — Download-Jar, which is where a bad -Version or an unreachable artifact is discovered, and which exit 1s (install.ps1:593)

Consequence

A typo in -Version, an artifact that does not exist for the chosen -EsVersion, or an Artifactory outage leaves roughly 300 MB of orphaned jdk\ in the target directory. There is no uninstaller, and nothing in the failure output mentions that a JDK was left behind, so the user is not told what to delete or that there is anything to delete.

It compounds with the re-download issue: the orphan is not reused on the next attempt either.

Suggested fix

Either

1. resolve the artifact version before bootstrapping a JDK (the version probe is a cheap HTTP call and it is the input most likely to be wrong), or
2. record that this run created <Target>\jdk and remove it on a failure path that never produced a working install.

Option 1 is the smaller change and also shortens the failure loop for the far more common "wrong version" mistake.

[fupelaqu]

Same bootstrap path: #233, #234.