Add Obsidian vault URL ingestion

[MakiDevelop]

What needs to be done

Extend ingest.py to scan an Obsidian vault directory and extract URLs from markdown files.

Which file(s) to modify

• ingest.py — add Obsidian scanning logic

Proposed approach

1. Add --obsidian /path/to/vault flag
2. Recursively find all .md files in the vault
3. Extract URLs using the existing extract_urls() function
4. Pass through normalize_url() → ingest_urls(source="obsidian")

Example usage

python3 ingest.py --obsidian ~/Documents/MyVault
python3 ingest.py --obsidian ~/Documents/MyVault --after 2024-01-01

Hints

• extract_urls() already handles URL extraction from text
• Obsidian markdown links look like [text](https://...) or bare URLs
• Consider adding --after date filter to avoid re-processing old notes
• Use pathlib.Path.rglob("*.md") for recursive file finding

Acceptance criteria

• Recursively scans .md files
• Extracts both [text](url) and bare URLs
• Uses existing extract_urls() for consistency
• Adds tests