Fix comm sort-order crash in package diffing; align minimal list with R 4.5

[jaempawi]

Two small fixes found while setting up a fresh macOS install.

1. pixi-setup.sh: comm: file 1 is not in sorted order

comm requires both inputs to be sorted. In inject_packages, the left-hand input is the output of pixi global list --json | jq | tr, which is never sorted:

comm -13 <(pixi global list --json --environment ${environment} | jq '...name' | tr -d '"') <(sort -u ${package_list})

This stays quiet on a first clean run, because the target env holds exactly one package at that point and a single line is trivially sorted. On any rerun into an env that already holds two or more packages, comm fails. With set -o errexit that kills the script outright, and since inject_packages r-base runs before inject_packages python, the Python section never executes at all.

Fix: sort the left-hand side, and pin LC_ALL=C on both sides of both comm calls so the two inputs cannot be collated differently on a machine with a non-C locale.

2. minimal_packages.txt: r-base 4.4 -> 4.5

The two lists disagreed: minimal pinned r-base=4.4 while full pins r-base=4.5. Anyone installed from the minimal list then cannot add r-pecotmr later, since every published build requires r-base >=4.5,<4.6.0a0:

r-pecotmr 0.7.7 | 0.7.8 would require
  r-base >=4.5,<4.6.0a0, for which no candidates were found

Bumping minimal to 4.5 makes the two lists agree and keeps the minimal env forward-compatible. Happy to drop this commit if the 4.4 pin was deliberate.