Trim comments across configs and services

Shorten verbose multi-paragraph comments to essentials, and drop a
stale claim in common.nix that jupiter kept its own copy of the base
config (it now imports common.nix directly).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

services/prowlarr.nix

@@ -1,23 +1,16 @@
 { ... }:
 
 # Prowlarr — indexer manager (usenet + torrent), feeds SABnzbd/MediaManager.
-# services.prowlarr.dataDir is left at its module default (/var/lib/prowlarr)
-# on purpose: passing a *custom* dataDir makes the upstream module bind-mount
-# it and force-reset the outer dir to 0700 root:root via a tmpfiles rule on
-# every boot (nixos/modules/services/misc/servarr/prowlarr.nix) — that stomps
-# DynamicUser's access to pre-existing content and causes intermittent
-# "unable to open database file".
-#
-# Instead we bind-mount the real (migrated-from-ZimaOS) config dir straight
-# onto the module's own default path, so prowlarr never sees a "custom"
-# dataDir and none of that logic triggers. DynamicUser+StateDirectory then
-# recursively chowns the pre-existing content to its assigned uid on first
-# activation, same as it does for a fresh install — no manual chown needed.
+# dataDir is left at the module default: a *custom* dataDir makes the
+# upstream module force-reset it to 0700 root:root on every boot, stomping
+# DynamicUser's access ("unable to open database file"). Instead bind-mount
+# the real (migrated-from-ZimaOS) config dir onto the default path, so
+# DynamicUser+StateDirectory chowns it on first activation like a fresh
+# install — no manual chown needed.
 #
 # Mount onto /var/lib/private/prowlarr, NOT the public /var/lib/prowlarr:
-# DynamicUser+StateDirectory keeps real data at .../private/<name> and makes
-# the public path a symlink to it; binding onto the public path turns it into
-# a mountpoint systemd then can't rename during its migrate-on-start dance
+# StateDirectory symlinks the public path to .../private/<name>; binding
+# onto the public path itself blocks systemd's migrate-on-start rename
 # ("Device or resource busy", exit 238/STATE_DIRECTORY).
 {
   services.prowlarr.enable = true;