Fix vendor package, release lookup and PATH defects in bootstrap.sh

A full run against Ubuntu 26.04 exposed several failures, every one of
which left the machine silently incomplete rather than reporting an
error.

azure-cli, powershell and gh were installed in a single apt-get call,
and azure-cli is not carried in Microsoft's prod feed. apt therefore
installed none of the three, and the warning blamed all of them. Add
the dedicated azure-cli repository and install one package per call.

glab was looked up on github.com/gitlab-org/cli, a read-only mirror
that publishes no releases at all, so its tag could never resolve and
the download URL came out malformed every time. Add gl_latest, which
reads GitLab's release permalink instead.

Resolve GitHub tags from the /releases/latest redirect rather than the
API, which allows only 60 unauthenticated requests an hour per address.

Install starship into ~/.local/bin. Its installer calls sudo -v to
pre-validate, and sudo -v prompts for a password even under
NOPASSWD:ALL because it matches no specific command. With no TTY that
blocks forever instead of failing, hanging the entire run.

Try dotnet-sdk-10.0 first, since the 9.0 and 8.0 series are retired for
noble.

Correct verify, which reported az as present when only the Windows
binary on the inherited WSL PATH existed, and which checked for a
binary named graphviz that the package never ships. It now rejects
/mnt/ resolutions, checks dot, covers the PowerShell modules, and exits
non-zero so that it can gate.

Restore the documented PATH precedence. brew shellenv prepends its own
bin ahead of /usr/bin, so apt packages did not in fact shadow brew
formulae of the same name. Rewrite the managed .bashrc block on every
run rather than skipping it when present, because a block that can only
be appended can never be corrected on a machine already provisioned.

Guard the download and unpack helpers so that one unavailable asset
warns and continues rather than aborting the run, as the standing rule
for a failing repository already requires.

Add shellcheck and xz-utils to the toolchain, add a psmodules section
installing Az, Microsoft.Graph, Pester and LibreDevOpsHelpers, and
remove yt-dlp.

Author: craigthackerx