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).

internal/docpipe/pdfattach_test.go

@@ -105,10 +105,10 @@ func TestXMLToText(t *testing.T) {
 	raw := []byte(`<?xml version="1.0" encoding="UTF-8"?>
 <rsm:CrossIndustryInvoice><rsm:ExchangedDocument>
 <ram:ID>S1063</ram:ID></rsm:ExchangedDocument>
-<ram:Name>Edelweiss &amp; Co</ram:Name><ram:GrandTotalAmount>42.00</ram:GrandTotalAmount>
+<ram:Name>Acme &amp; Co</ram:Name><ram:GrandTotalAmount>42.00</ram:GrandTotalAmount>
 </rsm:CrossIndustryInvoice>`)
 	got := xmlToText(raw)
-	for _, want := range []string{"S1063", "Edelweiss & Co", "42.00"} {
+	for _, want := range []string{"S1063", "Acme & Co", "42.00"} {
 		if !strings.Contains(got, want) {
 			t.Errorf("xmlToText missing %q:\n%s", want, got)
 		}