feat: v0.2.0 — DOCX/XLSX/CSV extraction, HTML format, multi-URL watch, batch LLM

Document extraction:
- DOCX: auto-detected, outputs markdown with headings (via zip + quick-xml)
- XLSX/XLS: markdown tables with multi-sheet support (via calamine)
- CSV: quoted field handling, markdown table output
- All auto-detected by Content-Type header or URL extension

New features:
- -f html output format (sanitized HTML)
- Multi-URL watch: --urls-file + --watch monitors all URLs in parallel
- Batch + LLM: --extract-prompt/--extract-json works with multiple URLs
- Mixed batch: HTML pages + DOCX + XLSX + CSV in one command

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/webclaw-fetch/Cargo.toml

@@ -19,6 +19,8 @@ url = "2"
 rand = "0.8"
 quick-xml = { version = "0.37", features = ["serde"] }
 serde_json.workspace = true
+calamine = "0.34"
+zip = "2"
 
 [dev-dependencies]
 tempfile = "3"