Create flake, packages and services namespaces

Selectively inherit some of the less niche functions to the root level

Add lib.getStandaloneHomeConfigurations and lib.isStandaloneHome

Configure agenix-rekey to only consider standalone homes to avoid dummy
host warning on unused host-based home configurations

Modify ciMatrix package to use the new standalone home functions

For whatever reason that one package still infrecs unless I override it
manually

For some reason, the officially recommended overlay causes opaque
infinite recursion errors in some cases, but luckily a
[workaround](https://github.com/NixOS/nixpkgs/pull/445223#issuecomment-3330902652)
exists

Remove unused hyprland input

Add nixpkgs follows

Change back to more manually assembled outputs for better control of the
overridden attributes

Create lib.callPackageRecursiveWith to wrap
lib.packagesFromDirectoryRecursive so that it works more like the
existing callPackageWith

Create lib.callPackageWith to make it automatically attempt to load a
subdir's package.nix or default.nix if present

Reintroduce package overlay and make it the default

Migrate outdated powerManagement.powerUpCommand and co to oneshot
services

Remove haumea and lib.loaders as those were obsolete, unnecessarily
complex and went mostly unused anyway

Create lib.nixFilesToAttrs for simple localized processing of nix files
in select locations instead, see nix/overlays/default.nix and
nix/legacyPackages/scripts/default.nix

Regenerates README with fixed obsolete content

Those are unnecessarily complex remnants that weren't being used anyway

Those never worked quite right, so I'll just use
pkgs-by-name-for-flake-parts for now

Specify builder image instead of using latest

Ensure system is passed as an input

Update lix-gha-installer

Should catch errors in the less often used home configs

A thin abstraction over agenix-rekey allows home-level keys to be
automatically used as host-level instead when applicable for easier
keying to the host's SSH key instead of each user's home SSH keys. That
only applies to home-manager configs used as NixOS modules, as standalone
home configurations still have to use the appropriate user-level key.
See my.secretDefinitions, my.secrets

All commands now use the new `@complete external`

Nushell has a built-in picker, but it's quite barebones, so I made this
to make use of fzf's niceties

Supports plain lists and tables, optionally takes a cell path to show a
desired column from a table

chore: Update flake inputs

Trying to work around sporadic aarch64 build failures

That was never meant to be there to begin with, oops

Rename nix/modules to the more appropriate nix/flakeModules

Move systems to an output instead of a privileged arg

Fix lib.loaders.load to actually take the filterFn into account

Demote kernel, pipewire, users, virtualization and wayland profiles to
regular modules, as it doesn't fit with the idea of orthogonal
generalized roles

Add assertions to DE/graphical/gui profiles so they aren't accidentally
activated without config.hardware.graphics.enable

Remove most of the "hidden enables" on my module namespace except where
a dependent option can be reasonably considered to be part of the base
feature set, enabled modules are now clear from skimming
`nix/{home,system}/modules/default.nix`. See `my.cli.editors` for the
most notable offender, as `my.cli.editors.enable` used to affect several
nested options.

Demote graphical profile to off by default as this flake provides configs
for both daily driver machines and servers

Rework `my.profiles.apps` namespace into `my.gui` for consistency

Home and NixOS configurations are now built only on main by default,
while packages and devShells build on main and develop

Now builds a list of derivations for each arch, ignores
nixosConfigurations for the moment

The CI derivation matrix is now built based on an explicitly set, per
derivation flag

For home/nixos configs, `config.my.ci.build = true` must be set.
For devShells/packages, `passthru.my.ci.build = true` will enable builds for
all systems. Use `passthru.my.ci.${system}.build = true` for more granular
control.