feat: add English vocab extraction and Anki card registration

- core/vocab.py: extract B1-B2 level vocabulary from English content via Gemini Flash
- core/anki.py: register vocab cards to AnkiConnect (English::Vocabulary deck)
- core/enricher.py: add language detection field + summary_ko (Korean summary)
- core/obsidian.py: render Korean + English summary in note
- daemon/worker.py: call vocab extraction and Anki registration for English content

core/anki.py

@@ -0,0 +1,106 @@
+"""AnkiConnect HTTP client for adding vocabulary cards."""
+
+import json
+import logging
+from urllib import request, error
+
+logger = logging.getLogger(__name__)
+
+ANKI_URL = "http://localhost:8765"
+DECK_NAME = "English::Vocabulary"
+MODEL_NAME = "Basic"
+
+
+def _invoke(action: str, **params) -> object:
+    """Call AnkiConnect API.
+
+    Args:
+        action: AnkiConnect action name.
+        **params: Action parameters.
+
+    Returns:
+        The result field from AnkiConnect response.
+
+    Raises:
+        RuntimeError: If AnkiConnect returns an error.
+    """
+    payload = json.dumps({"action": action, "version": 6, "params": params}).encode()
+    req = request.Request(ANKI_URL, payload, {"Content-Type": "application/json"})
+    with request.urlopen(req, timeout=5) as resp:
+        data = json.loads(resp.read())
+    if data.get("error"):
+        raise RuntimeError(f"AnkiConnect error: {data['error']}")
+    return data["result"]
+
+
+def _ensure_deck() -> None:
+    """Create deck if it doesn't exist."""
+    _invoke("createDeck", deck=DECK_NAME)
+
+
+def _build_front(word: str, pos: str, example: str) -> str:
+    return f"<b>{word}</b> <i>({pos})</i><br><br>{example}"
+
+
+def _build_back(definition_en: str, definition_ko: str) -> str:
+    return f"{definition_en}<br><br><b>한국어:</b> {definition_ko}"
+
+
+def add_vocab_cards(vocab_list: list[dict], source_title: str = "") -> list[int]:
+    """Add vocabulary cards to Anki.
+
+    Skips duplicates silently (AnkiConnect returns null for existing notes).
+
+    Args:
+        vocab_list: List of vocab dicts from extract_vocab().
+        source_title: Content title, added as a tag on each card.
+
+    Returns:
+        List of created note IDs (excludes skipped duplicates).
+    """
+    if not vocab_list:
+        return []
+
+    try:
+        _ensure_deck()
+    except error.URLError:
+        logger.warning("AnkiConnect unreachable — skipping vocab card creation")
+        return []
+
+    tag = source_title[:50].replace(" ", "_") if source_title else "knowledge-inbox"
+
+    notes = [
+        {
+            "deckName": DECK_NAME,
+            "modelName": MODEL_NAME,
+            "fields": {
+                "Front": _build_front(
+                    item.get("word", ""),
+                    item.get("pos", ""),
+                    item.get("example", ""),
+                ),
+                "Back": _build_back(
+                    item.get("definition_en", ""),
+                    item.get("definition_ko", ""),
+                ),
+            },
+            "options": {"allowDuplicate": False},
+            "tags": ["knowledge-inbox", tag],
+        }
+        for item in vocab_list
+        if item.get("word")
+    ]
+
+    try:
+        results = _invoke("addNotes", notes=notes)
+    except Exception as exc:
+        logger.error("Failed to add Anki cards: %s", exc)
+        return []
+
+    created = [note_id for note_id in results if note_id is not None]
+    skipped = len(results) - len(created)
+    logger.info(
+        "Anki: added %d card(s), skipped %d duplicate(s) for '%s'",
+        len(created), skipped, source_title[:40],
+    )
+    return created