feat(transcribe): add TranscribeCoachEmptyState and TranscribeDragDemo components

New coach card replaces the icon+sentence empty state in the Transcribe
panel (edit mode). Three-step guide with 5-s SMIL drawing animation in
step 1 only. Animation freezes at the final frame when
prefers-reduced-motion is active. Footer links to Wikipedia Kurrent and
the Richtlinien page open in new tabs with visible '(öffnet in neuem Tab)'
annotations. 34 new i18n keys in de/en/es.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/messages/en.json

@@ -810,5 +810,45 @@
 	"pagination_prev": "Previous",
 	"pagination_next": "Next",
 	"pagination_page_of": "Page {page} of {total}",
-	"pagination_nav_label": "Pagination"
+	"pagination_nav_label": "Pagination",
+
+	"common_opens_new_tab": "(opens in new tab)",
+
+	"transcribe_coach_title": "First transcription?",
+	"transcribe_coach_preamble": "Our Kurrent recogniser is still learning. Every transcription you release for training teaches it the handwriting — here's how it works:",
+	"transcribe_coach_step_1_title": "Draw a frame.",
+	"transcribe_coach_step_1_body": "Click and drag a frame around the text you want to transcribe.",
+	"transcribe_coach_step_2_title": "Enter the text.",
+	"transcribe_coach_step_2_body": "Type the text you see inside the frame into the new text field.",
+	"transcribe_coach_step_3_title": "Saves automatically.",
+	"transcribe_coach_footer_kurrent": "Kurrent help ↗",
+	"transcribe_coach_footer_richtlinien": "Transcription guidelines ↗",
+
+	"transcription_mode_help_label": "Read and edit mode",
+	"transcription_mode_help_body": "Read shows the transcription as flowing text. Edit opens the text fields for each passage.",
+
+	"richtlinien_title": "Transcription Guidelines",
+	"richtlinien_intro": "So every letter is transcribed consistently — whether Tante Hedwig or Cousin Paul is typing — here are our rules. The page grows with us: as soon as we agree a new convention, it lands here.",
+	"richtlinien_wiki_text": "You don't need the full Kurrent and Sütterlin alphabet on this page — that's what Wikipedia is for. Here are our own rules for everything Wikipedia can't answer.",
+	"richtlinien_wiki_link": "Wikipedia →",
+	"richtlinien_rules_label": "Transcription rules",
+	"richtlinien_rule_unleserlich_title": "Illegible words",
+	"richtlinien_rule_unleserlich_body": "If you can't decipher a word even after trying, write [unleserlich]. Someone else will take another look later.",
+	"richtlinien_rule_durchgestrichen_title": "Struck-through words",
+	"richtlinien_rule_durchgestrichen_body": "Struck-through text still belongs to the letter. Write it in square brackets with prefix durchgestrichen:",
+	"richtlinien_rule_langes_s_title": "The long s (ſ)",
+	"richtlinien_rule_langes_s_body": "The ſ is just an old written form of the letter s — not a separate sound. Always write a normal s.",
+	"richtlinien_rule_name_title": "Uncertain names",
+	"richtlinien_rule_name_body": "If you think you can read a name but aren't sure, add a question mark in square brackets.",
+	"richtlinien_rule_dialekt_title": "Dialect, foreign words, foreign quotes",
+	"richtlinien_rule_dialekt_body": "Low German, French, Latin phrases — copy them verbatim, exactly as written.",
+	"richtlinien_beispiel_label": "Example",
+	"richtlinien_klaerung_label": "Still to be decided",
+	"richtlinien_klaerung_intro": "These questions are still open — if you hit one while transcribing, make a plausible choice and note it in the comments:",
+	"richtlinien_klaer_abkuerzungen": "Abbreviations",
+	"richtlinien_klaer_datumsformate": "Date formats",
+	"richtlinien_klaer_umbrueche": "Original line breaks",
+	"richtlinien_klaer_caps": "Old capitalisation",
+	"richtlinien_closing_title": "Missing a rule?",
+	"richtlinien_closing_body": "If you hit a situation while transcribing that isn't listed here — leave a comment on the relevant block. We collect them and discuss them at the next family gathering."
 }