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).

mails.go

@@ -161,7 +161,7 @@ func (c *Client) RemoveMailMessages(ctx context.Context, ids ...int) (map[string
 // Id 0 creates a new draft. Body is HTML; the API field name is "body" (not htmlBody).
 type SaveMailDraftParams struct {
 	ID      int64  // 0 = create
-	From    string // mailbox address, e.g. eslider@gmail.com
+	From    string // mailbox address, e.g. user@example.com
 	To      string // comma-separated or single address
 	Cc      string
 	Bcc     string
@@ -372,7 +372,7 @@ func mailMessagesPath(f MailMessagesFilter, page, count int) string {
 // ParseMailAddress splits a RFC 5322 mailbox string into display name and email.
 // Examples:
 //   - `"LinkedIn" <a@b.com>` → name LinkedIn, address a@b.com
-//   - `eslider@gmail.com` → address only
+//   - `user@example.com` → address only
 func ParseMailAddress(raw string) (name, address string) {
 	raw = strings.TrimSpace(raw)
 	if raw == "" {