feat(translation): quality pipeline overhaul + new features (audit 2026-08-29)

Translation quality & format preservation:
- Word: merge adjacent same-format runs into one unit (sentence-level
  coherence like inline-tag handling); translate comments/balloons;
  dedupe textbox collection (was translated twice); RTL no longer
  overrides center/justify alignment; CJK/Arabic font hints (eastAsia/cs)
- PPTX: chart translations now actually reach the output file
  (ChartPart.blob is read-only — rewrite chart XML in the saved ZIP);
  CJK typeface hints (a:ea)
- Excel: sheet renames no longer break references — rewrite cell
  formulas (3D/quoted), defined names, data validations, cond. formats
- PDF: bold/italic honored (hebo/heit/hebi); table cells never merge;
  unchanged blocks left untouched (typography preserved, fixes duplicate
  hyperlinks); attempted/changed stats + route gate now cover PDF;
  CJK font paths; scanned PDFs via Mistral OCR (detection + admin settings)

Features:
- formality param (formal/informal) + automatic regional-variant prompts
- output_mode=bilingual docx (source above translation)
- per-user translation memory on Redis (falls back to LRU), context-hashed
- QA report + 0-100 confidence score in job status; L0 on by default
- OpenAI-compatible providers: whole chunk in ONE numbered-JSON request
  (~15x fewer calls) with per-item fallback; base prompt always present
  (custom prompt no longer replaces translation instructions)

Infra & marketing alignment:
- plan-based engine gating + vision gating (closes paid-engine leak);
  /providers/available filtered per plan; 107 languages exposed
- zh-CN/zh-TW validation fixed; libmagic disabled on Windows (native crash)
- admin: Mistral OCR settings + engine status dashboard; httpx<0.28 pin
  (TestClient breakage); Prometheus test fixture fixed
- marketing docs aligned with code (PDF+OCR, retention, engines, pricing)
- security: .env.ionos/.env.production/provider_settings.json removed

Tests: 1173 passed / 0 failed (6 network tests deselected: free Google
endpoint temporarily blocked from this machine)

core/languages.py

@@ -0,0 +1,137 @@
+"""
+Language display names for LLM prompts and UI labels.
+
+Single source of truth for code → English name across providers. The map
+covers every code exposed by /api/v1/languages (SUPPORTED_LANGUAGES), so
+prompts say "Translate to Tagalog" instead of "Translate to tl" — LLMs
+translate noticeably better with full language names.
+"""
+
+from typing import Dict
+
+LANGUAGE_NAMES: Dict[str, str] = {
+    "af": "Afrikaans",
+    "sq": "Albanian",
+    "am": "Amharic",
+    "ar": "Arabic",
+    "hy": "Armenian",
+    "az": "Azerbaijani",
+    "eu": "Basque",
+    "be": "Belarusian",
+    "bn": "Bengali",
+    "bs": "Bosnian",
+    "bg": "Bulgarian",
+    "ca": "Catalan",
+    "ceb": "Cebuano",
+    "zh": "Chinese",
+    "zh-CN": "Chinese (Simplified)",
+    "zh-TW": "Chinese (Traditional)",
+    "co": "Corsican",
+    "hr": "Croatian",
+    "cs": "Czech",
+    "da": "Danish",
+    "nl": "Dutch",
+    "en": "English",
+    "eo": "Esperanto",
+    "et": "Estonian",
+    "fi": "Finnish",
+    "fr": "French",
+    "fy": "Frisian",
+    "gl": "Galician",
+    "ka": "Georgian",
+    "de": "German",
+    "el": "Greek",
+    "gu": "Gujarati",
+    "ht": "Haitian Creole",
+    "ha": "Hausa",
+    "haw": "Hawaiian",
+    "he": "Hebrew",
+    "hi": "Hindi",
+    "hmn": "Hmong",
+    "hu": "Hungarian",
+    "is": "Icelandic",
+    "ig": "Igbo",
+    "id": "Indonesian",
+    "ga": "Irish",
+    "it": "Italian",
+    "ja": "Japanese",
+    "jv": "Javanese",
+    "kn": "Kannada",
+    "kk": "Kazakh",
+    "km": "Khmer",
+    "rw": "Kinyarwanda",
+    "ko": "Korean",
+    "ku": "Kurdish",
+    "ky": "Kyrgyz",
+    "lo": "Lao",
+    "la": "Latin",
+    "lv": "Latvian",
+    "lt": "Lithuanian",
+    "lb": "Luxembourgish",
+    "mk": "Macedonian",
+    "mg": "Malagasy",
+    "ms": "Malay",
+    "ml": "Malayalam",
+    "mt": "Maltese",
+    "mi": "Maori",
+    "mr": "Marathi",
+    "mn": "Mongolian",
+    "my": "Myanmar (Burmese)",
+    "ne": "Nepali",
+    "no": "Norwegian",
+    "ny": "Nyanja (Chichewa)",
+    "or": "Odia (Oriya)",
+    "ps": "Pashto",
+    "fa": "Persian (Farsi)",
+    "pl": "Polish",
+    "pt": "Portuguese",
+    "pa": "Punjabi",
+    "ro": "Romanian",
+    "ru": "Russian",
+    "sm": "Samoan",
+    "gd": "Scots Gaelic",
+    "sr": "Serbian",
+    "st": "Sesotho",
+    "sn": "Shona",
+    "sd": "Sindhi",
+    "si": "Sinhala",
+    "sk": "Slovak",
+    "sl": "Slovenian",
+    "so": "Somali",
+    "es": "Spanish",
+    "su": "Sundanese",
+    "sw": "Swahili",
+    "sv": "Swedish",
+    "tl": "Filipino (Tagalog)",
+    "tg": "Tajik",
+    "ta": "Tamil",
+    "tt": "Tatar",
+    "te": "Telugu",
+    "th": "Thai",
+    "tr": "Turkish",
+    "tk": "Turkmen",
+    "uk": "Ukrainian",
+    "ur": "Urdu",
+    "ug": "Uyghur",
+    "uz": "Uzbek",
+    "vi": "Vietnamese",
+    "cy": "Welsh",
+    "xh": "Xhosa",
+    "yi": "Yiddish",
+    "yo": "Yoruba",
+    "zu": "Zulu",
+}
+
+
+def language_name(code: str) -> str:
+    """Full English name for a language code; case-insensitive lookup.
+
+    Falls back to the code itself for unknown values (and "" for auto/None,
+    which callers use to mean "detect the source language").
+    """
+    if not code or code == "auto":
+        return ""
+    name = LANGUAGE_NAMES.get(code)
+    if name is None:
+        name = LANGUAGE_NAMES.get(code.split("-")[0].lower(), code)
+    return name