feat(wizard): optional AcoustID key step for metadata enrichment

Adds a wizard step (after the ML step) that prompts for an AcoustID API
key. Left blank, enrichment runs on embedded tags only; with a key the
backend also identifies untagged files by audio fingerprint (§1D). The
key is appended to .env.deploy and reaches both api and worker via
env_file. en/ru strings included.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

i18n/en.sh

@@ -99,6 +99,11 @@ MSG[admin_skip_note]="You can create an admin later with: make logs (see README)
 MSG[step_ml]="Optional ML service"
 MSG[ml_prompt]="ML service URL (leave blank — backend degrades gracefully)"
 
+# -- enrichment / acoustid -------------------------------------------------
+MSG[step_enrichment]="Metadata enrichment (optional)"
+MSG[enrichment_note]="Imported files are auto-tagged from their embedded tags. Add an AcoustID key to also identify untagged files by audio fingerprint (free: https://acoustid.org/new-application)."
+MSG[acoustid_prompt]="AcoustID API key (leave blank to use embedded tags only)"
+
 # -- summary / run ---------------------------------------------------------
 MSG[summary_title]="Summary (secrets hidden)"
 MSG[summary_services]="Services"