docs: condense comments across the repo

Comments had drifted into multi-paragraph narrative (git commit
lineage, debugging stories, restated code) in several hot spots
(scripts/deploy, hermes-agent.nix, flake.nix, gitea.nix, headscale.nix).
Trim every comment to its load-bearing "why" — gotchas, safety
warnings, and non-obvious rationale survive verbatim in substance,
just tightened to 1-2 sentences; historical narrative and anything
already covered in CLAUDE.md is cut. No code/logic changed.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UJqEmY1y3AYX3JoX4Y6b21

services/media/sonarr.nix

@@ -1,11 +1,10 @@
 { ... }:
 
-# Sonarr — TV library manager, feeds off SABnzbd/Prowlarr. dataDir points at
-# the config migrated from the old ZimaOS docker stack (indexers/download
-# client/history already set up). Unlike prowlarr, this module uses a static
-# `sonarr` user (no DynamicUser) and only auto-chowns dataDir when it's the
-# module's own default path — since we point at a pre-existing migrated dir,
-# chown it by hand once after first deploy:
+# Sonarr — TV library manager, feeds off SABnzbd/Prowlarr; dataDir points at
+# config migrated from the old ZimaOS docker stack. Unlike prowlarr, this
+# module uses a static `sonarr` user (no DynamicUser) and only auto-chowns
+# dataDir at its own default path, so the migrated dir needs a manual
+# one-time chown after first deploy:
 #   chown -R sonarr:sonarr /mnt/data/AppData/sonarr/config
 {
   services.sonarr = {