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/kontolink/main.go

@@ -76,7 +76,15 @@ func nearest(cands []entry, rd time.Time) (entry, bool) {
 	return cands[best], true
 }
 
-const linkPrefix = "https://office.pro-dukt.de/Products/Files/DocEditor.aspx?fileid="
+// portalBaseFromEnv resolves the portal base URL used to build document links.
+func portalBaseFromEnv() string {
+	for _, k := range []string{"ONLYOFFICE_URL", "ONLYOFFICE_HOST", "OO_URL"} {
+		if v := strings.TrimSpace(os.Getenv(k)); v != "" {
+			return strings.TrimRight(v, "/")
+		}
+	}
+	return ""
+}
 
 type entry struct {
 	id, path, title, norm string
@@ -91,6 +99,12 @@ func main() {
 	}
 	in, idxPath, out := os.Args[1], os.Args[2], os.Args[3]
 
+	portal := portalBaseFromEnv()
+	if portal == "" {
+		fmt.Fprintln(os.Stderr, "set ONLYOFFICE_URL (or ONLYOFFICE_HOST/OO_URL) to build document links")
+		os.Exit(2)
+	}
+
 	idxRaw, err := os.ReadFile(idxPath)
 	if err != nil {
 		panic(err)
@@ -153,7 +167,7 @@ func main() {
 			continue
 		}
 		ref, _ := excelize.CoordinatesToCellName(8, i+1)
-		if err := f.SetCellValue(sheet, ref, linkPrefix+e.id); err != nil {
+		if err := f.SetCellValue(sheet, ref, portal+"/Products/Files/DocEditor.aspx?fileid="+e.id); err != nil {
 			panic(err)
 		}
 		used[e.id] = true