Finish v4 upgrade cleanup

docs/file-layout.md

@@ -67,6 +67,7 @@ version                        ──►  omarchy             /usr/share/omarchy
 
 config/**                      ──►  omarchy-settings    /etc/skel/.config/**         (seeds new users)
                                                         /usr/share/omarchy/config/** (resync source)
+etc/fastfetch/config.jsonc     ──►  omarchy-settings    /etc/fastfetch/config.jsonc
 
 applications/*.desktop         ──►  omarchy-settings    /etc/skel/.local/share/applications/
                                                         /usr/share/omarchy/applications/
@@ -267,8 +268,10 @@ brand-new user, so this one copy resyncs `.bashrc`, `.config/**`,
 branding files, and the shipped migration markers in a single pass.
 
 Then it runs `omarchy-refresh-limine`, `omarchy-refresh-plymouth`, and the
-nvim refresh. Destructive: existing user files at these paths are clobbered
-without backup.
+nvim refresh. Destructive: existing user files copied from `/etc/skel` are
+clobbered without backup. Fastfetch is package-owned at
+`/etc/fastfetch/config.jsonc`; delete `~/.config/fastfetch/config.jsonc` to
+return to the packaged default.
 
 ## Quick reference: where does X live?
 

docs/migrations.md

@@ -4,13 +4,6 @@ Omarchy migrations are one-time repair scripts for existing installs. They are
 used when a package update needs to change state that pacman cannot safely own by
 itself.
 
-They are for both humans and agents:
-
-- Users should know when migrations run, where state is stored, and how to retry
-  or inspect pending work.
-- Agents should know which migration scope to use, how to write safe migration
-  scripts, and what should **not** be a migration.
-
 ## The two migration scopes
 
 Omarchy migrations are split by execution context:
@@ -32,6 +25,8 @@ Use system migrations for machine-wide state, for example:
 - hardware quirks
 - package-owned layout transitions
 
+Note that it's not necessary to write a migration for any file that will be package-owned.
+
 State lives in:
 
 ```text
@@ -177,6 +172,8 @@ Migrations are plain shell files:
 - no shebang
 - start with an `echo` describing the migration
 - use `$OMARCHY_PATH` for Omarchy-owned files
+- should be idempotent
+- should be as simple as possible to accomplish the task
 
 Example system migration: