chore: drop HOST overrides, move known issue to docs, tidy comments and gitignores

- Remove HOST=${SERVICE_HOSTNAME} from code-server, code-server-lsio and paseo; hostname: alone sets the name
- Move SERVICE_HOSTNAME to the top of their .env.example to match compose order
- Drop the openclaw ARM64 Chromium note from its README; docs/openclaw covers it
- List CUSTOM_USER in webtop's setup step
- Trim reasoning from diun and paseo comments
- Delete stale gitea and gitea-mirror .gitignore files
- Add TODO.md for remaining naming and README issues

code-server/.env.example

@@ -2,6 +2,9 @@
 #
 #   cp .env.example .env
 
+# Container hostname.
+SERVICE_HOSTNAME=code-server
+
 # Web UI login password. Required.
 # Generate one with: openssl rand -base64 24
 PASSWORD=
@@ -10,8 +13,5 @@ PASSWORD=
 GIT_NAME=
 GIT_EMAIL=
 
-# Container hostname, also passed in as HOST -- the name zsh's prompt shows.
-SERVICE_HOSTNAME=code-server
-
 # Name shown in the title bar and welcome page.
 # CODE_SERVER_APP_NAME=code-server