feat: initial knowledge-inbox pipeline implementation

- Oracle ADB queue table (sql/schema.sql)
- Queue CRUD: core/queue_db.py
- YouTube transcript: core/youtube.py
- Web page fetch: core/web.py
- LLM enrichment via OCI GenAI Gemini Flash: core/enricher.py
- Text chunker: core/chunker.py
- Obsidian note writer: core/obsidian.py
- Oracle vector store insertion: core/vector.py
- Polling daemon: daemon/worker.py
- Telegram bot: bot/telegram_bot.py
- Main runner: main.py

core/obsidian.py

@@ -0,0 +1,86 @@
+"""Save processed knowledge items as Obsidian markdown notes."""
+
+import os
+import re
+from datetime import datetime
+from pathlib import Path
+
+
+def _slugify(text: str, max_len: int = 50) -> str:
+    """Convert text to a filesystem-safe slug."""
+    text = re.sub(r"[^\w\s-]", "", text, flags=re.UNICODE)
+    text = re.sub(r"[\s_]+", "-", text).strip("-")
+    return text[:max_len].lower()
+
+
+def save_note(
+    content_type: str,
+    title: str,
+    summary: str,
+    body: str,
+    tags: list[str],
+    source_url: str = "",
+    author: str = "",
+    date: str = "",
+) -> Path:
+    """Save a processed knowledge item as an Obsidian markdown file.
+
+    Args:
+        content_type: One of 'youtube', 'url', 'text'.
+        title: The note title.
+        summary: LLM-generated summary.
+        body: Full content text.
+        tags: List of topic tags.
+        source_url: Original URL (empty for plain text).
+        author: Author name (may be empty).
+        date: Publication date in ISO 8601 format (may be empty).
+
+    Returns:
+        Path of the created markdown file.
+    """
+    vault = os.environ.get("OBSIDIAN_VAULT", "/Users/joungmin/Documents/Obsidian Vault")
+    today = datetime.now().strftime("%Y-%m-%d")
+    now_str = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+    slug = _slugify(title) or "untitled"
+
+    # Determine subfolder by content type
+    subfolder_map = {
+        "youtube": "20 Sources/YouTube",
+        "url": "20 Sources/Web",
+        "text": "20 Sources/Notes",
+    }
+    subfolder = subfolder_map.get(content_type, "20 Sources/Notes")
+    note_dir = Path(vault) / subfolder
+    note_dir.mkdir(parents=True, exist_ok=True)
+
+    filename = f"{today}-{slug}.md"
+    note_path = note_dir / filename
+
+    # Build YAML frontmatter tags
+    tags_yaml = ", ".join(tags) if tags else ""
+
+    content = f"""---
+title: {title}
+source_type: {content_type}
+url: {source_url}
+author: {author}
+date: {date}
+tags: [{tags_yaml}]
+created: {today}
+---
+
+# {title}
+
+## 요약
+{summary}
+
+## 원문
+{body}
+
+---
+*Source: {source_url}*
+*Saved: {now_str}*
+"""
+
+    note_path.write_text(content, encoding="utf-8")
+    return note_path