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/kontoblatt/main.go

@@ -162,7 +162,7 @@ func main() {
 	}
 	fmt.Printf("source: id=%s title=%q folder=%s\n", fileID, title, folder)
 
-	name := "Kontoblatt-1591-2025-Zusammenfassung.xlsx"
+	name := "Kontoblatt-Zusammenfassung.xlsx"
 	tmp := "/tmp/opencode/" + name
 	data, _ := os.ReadFile(outPath)
 	if err := os.WriteFile(tmp, data, 0o600); err != nil {