docs: add wiki, complete lib nav, and rebuild mcp artifacts

- Add hand-written wiki (index, overview, how-to, extending, dev) with
  MkDocs config following the platform anatomy
- Complete the library nav by registering the csv and xlsx groups in
  docforge.nav.yml and docs/mkdocs.lib.yml
- Regenerate lib/MCP outputs with the rebuilt nav

docs/wiki/02_how_to_use.md

@@ -0,0 +1,109 @@
+# 🖥️ How to Use
+
+Every format follows the same pipeline: **scrape → `Content` → parse**.
+This page shows each supported format with working patterns.
+
+---
+
+## 🌐 HTML
+
+```python
+from omniread import HTMLScraper, HTMLParser
+
+class TitleParser(HTMLParser[str]):
+    def parse(self) -> str:
+        return self._soup.title.string
+
+scraper = HTMLScraper()                     # httpx under the hood
+content = scraper.fetch("https://example.com")
+
+title = TitleParser(content).parse()
+```
+
+`HTMLScraper` accepts an optional `client` (an `httpx.Client`) for transport
+control — the test suite wires one to a mock transport.
+
+---
+
+## 📕 PDF
+
+PDFs need a **client** to supply raw bytes before parsing:
+
+```python
+from pathlib import Path
+from omniread import FileSystemPDFClient, PDFScraper, PDFParser
+
+class TextPDFParser(PDFParser[str]):
+    def parse(self) -> str:
+        # implement your extraction logic
+        return self.content.raw  # bytes, decode as needed
+
+client = FileSystemPDFClient()
+scraper = PDFScraper(client=client)
+content = scraper.fetch(Path("document.pdf"))
+
+result = TextPDFParser(content).parse()
+```
+
+`PDFParser` subclasses receive `self.content` and implement `parse()`.
+
+---
+
+## 📊 CSV
+
+```python
+from omniread import FileSystemCsvClient, CsvScraper, CsvParser
+
+scraper = CsvScraper(client=FileSystemCsvClient())
+content = scraper.fetch("data.csv")
+
+parser = CsvParser(content)
+for row in parser.rows():
+    print(row)
+```
+
+`CsvParser.rows()` yields string rows trimmed of empties by default
+(`skip_empty=True`).
+
+---
+
+## 📑 XLSX
+
+```python
+from omniread import FileSystemXlsxClient, XlsxScraper, XlsxParser
+
+scraper = XlsxScraper(client=FileSystemXlsxClient())
+content = scraper.fetch("statement.xlsx")
+
+parser = XlsxParser(content)
+print(parser.sheet_names)                 # e.g. ["Statement"]
+rows = parser.rows(sheet="Statement")     # by name or index
+all_rows = parser.parse()                 # alias for rows()
+```
+
+Key behaviors:
+
+- `rows(skip_empty=False)` keeps blank rows (off by default).
+- Cells render as trimmed strings; date cells convert to ISO format
+  (`2026-06-01T00:00:00`).
+- `rows(sheet="Missing")` raises for an unknown sheet.
+
+---
+
+## 🔀 End-to-end flow
+
+```python
+content = scraper.fetch(source)   # 1. acquire → Content
+assert isinstance(content.raw, bytes)
+assert content.content_type is not None
+
+parser = MyParser(content)        # 2. interpret → T
+result = parser.parse()
+```
+
+---
+
+## 📚 Read Next
+
+- [Overview](01_overview.md) — the full architecture.
+- [Extending OmniRead](03_extending.md) — custom clients and parsers.