chore: keep host/client specifics out of the tree (env & config)

Showroom-safe: the tree no longer carries internal hosts, IPs, ports,
personal names, client domains or client file names. Behaviour is
unchanged and now supplied per deployment.

- catalog: hardcoded mail-org / project classifiers become a YAML-driven
  Classifier (OO_CATALOG_CONFIG or --config); neutral default classifies
  nothing as work. New catalog/classify.go + example + tests.
- storage_fallback: drop the baked-in MinIO endpoint IP; require
  MINIO_ENDPOINT (+ keys) from the env.
- kontolink: build DocEditor links from $ONLYOFFICE_URL instead of a
  hardcoded portal host; kontoblatt: no client file id in the output name.
- oo: load .env CLI-wide (bootstrap.LoadEnv in execute) so
  non-authenticating commands (catalog scans) also see config.
- genericize comments/docs/fixtures (AGENTS, README, .env.example,
  crm-associations, catalog tests, ES/pdfattach tests, mails).

cmd/oo/common.go

@@ -31,7 +31,9 @@ func init() {
 }
 
 // execute runs the root command. Exported only to main.go in the same package.
-func execute() error { return rootCmd.Execute() }
+// .env is loaded CLI-wide so non-authenticating commands (e.g. catalog scans)
+// also see configuration such as OO_CATALOG_CONFIG.
+func execute() error { bootstrap.LoadEnv(); return rootCmd.Execute() }
 
 // newOO loads env (only .env in CWD) and returns an authenticated client.
 // godotenv is a CLI-only concern; the library itself never loads dotfiles.