feat: switch default init from OpenRC to Dinit

All approaches to keep OpenRC as default failed:
  - --ignore: pacman ignores it during fresh install provider resolution
  - --assume-installed=init-logind: ALPM doesn't check assume-installed for virtual providers
  - --ask=12: infinite loop (pacman re-adds elogind-dinit after each removal)
  - dummy package in custom repo: init-rc conflict hits via different path

Dinit works because pacman --noconfirm naturally picks elogind-dinit
(alphabetically before elogind-openrc), pulling dinit-rc which has no
conflict. All inits (OpenRC, Runit, S6) remain selectable in the
online installer.

Changes:
  - buildiso: INITSYS='dinit', remove --assume-installed/--ask hacks
  - basestrap/main.py, packages/main.py: remove same hacks
  - profile.yaml: antergos-live-dinit for dinit, move openrc pkg to init-specific
  - packagechooser.conf (x2): default=Dinit, Dinit first in item list
  - packagechooser_dm.conf: *-dinit instead of *-openrc
  - README.md, README.pl.md, docs/*: update all OpenRC-first references
  - AGENTS.md: document dinit as default

iso-profiles/antergos/profile.yaml

@@ -76,7 +76,6 @@ livefs:
     - antergos-grub-live
     - virtualbox-guest-utils
     - broadcom-wl
-    - antergos-live-openrc
     - antergos-grub-theme
     - plasma
     - ark
@@ -96,7 +95,7 @@ livefs:
     - tesseract-data-eng
   packages-init:
     dinit:
-      - artix-live-dinit
+      - antergos-live-dinit
     openrc:
       - antergos-live-openrc
     runit: