feat: build each doc kind with its own MkDocs config and site

docs/wiki/04_iterative_workflow.md

@@ -8,7 +8,7 @@ A docs build runs through the CLI in a single pass.
 # Library reference only
 doc-forge build --mkdocs --module docforge
 
-# Wiki + library combined (single MkDocs build)
+# Wiki + library (each an independent MkDocs build)
 doc-forge build --wiki --mkdocs --module docforge
 
 # Wiki only — no module required
@@ -18,21 +18,26 @@ doc-forge build --wiki --site-name docforge
 doc-forge build --mcp --module docforge
 ```
 
-## What a combined build does
+## What a build does
 
 1. Validates the requested modes (`--mkdocs`, `--api`, `--wiki`, `--mcp`).
 2. Generates library sources under `docs/lib/**` with `MkDocsRenderer`.
 3. Generates API sources under `docs/api/**` when `--api` is given.
-4. Derives wiki navigation from `docs/wiki/**`.
-5. Writes `mkdocs.yml` with merged navigation — wiki first, generated groups
-   appended, and the wiki `Home` replacing any spec `Home` entry.
-6. Runs `mkdocs build` once and emits the site.
+4. Derives the wiki navigation from `docs/wiki/**`.
+5. Writes one MkDocs config per site kind (`docs/mkdocs.{lib,api,wiki}.yml`),
+   re-rooting navigation paths to each kind's `docs_dir`.
+6. Runs `mkdocs build` once per config, emitting self-contained sites
+   `site/lib/`, `site/api/`, and `site/wiki/`.
 
-## Explore the site
+## Explore the sites
 
 ```bash
 doc-forge build --wiki --mkdocs --module docforge
-doc-forge serve --mkdocs --mkdocs-yml mkdocs.yml
+doc-forge serve --wiki       # serves site preview from docs/mkdocs.wiki.yml
+doc-forge serve --lib
+doc-forge serve --api
+# or target any config directly:
+doc-forge serve --mkdocs --mkdocs-yml docs/mkdocs.wiki.yml
 ```
 
 ## Serve the MCP bundle