refactor(meta): flatten groups; only break out optional/hw-specific

Drop the per-domain group fragmentation in meta/ and the parallel
group-per-file structure in systemd-units/.

  meta/ (18 -> 6 groups):
    keep    base, flatpak (magic), intel, nvidia, work, btc
    fold    browser, bt, cpp, dev, extra, fonts, mail, media, nix,
            sound, wayland -> base (with `# --- section ---` comments
            preserving at-a-glance structure)
    drop    fortran (niche; install ad-hoc when needed)

  systemd-units/:
    flatten to a single system.txt + user.txt; .ignore files move up
    one level; group concept and pairing rule removed.

  justfile:
    unit-list/unit-apply/unit-status no longer take a group argument.
    unit-add/unit-forget infer scope by probing
    `systemctl [--user] cat <unit>` (system wins on tie). Top-level
    add/forget dispatcher updated: any unit-suffixed arg routes to
    unit-* without requiring a leading GROUP.

  docs:
    .github/copilot-instructions.md and README.md updated to describe
    the new flat layout. Pairing rule and group-token grammar gone.

Pure layout refactor - no package contents change.

1 files changed, 0 insertions, 24 deletions

diff --git a/meta/dev.txt b/meta/dev.txt
deleted file mode 100644
index 5f26ad7..0000000
--- a/meta/dev.txt
+++ /dev/null
@@ -1,24 +0,0 @@
-android-tools
-curl
-difftastic
-direnv
-git-absorb
-git-delta
-github-cli
-go
-hyperfine
-jdk-openjdk
-just
-luarocks
-mergiraf
-mold
-npm
-podman-compose
-podman-docker
-rust-analyzer
-rustup
-samply
-sccache
-strace
-t-rec
-uv