docs: split project reports, pin checker links

Reading this project's own reports gets its own page. Checker code is linked at the revision each platform list was read from. Installer moves to Your setup, legal to Start here, build internals to Contribute, and Reference pages carry a group.

wiki/testing-guide.md

@@ -1,7 +1,6 @@
 ---
 level: contribute
 order: 40
-nav_title: Testing
 ---
 
 # Testing guide
@@ -56,7 +55,7 @@ Every module in `tests/`, by the area it guards.
 | Handheld port | stubbed PortMaster dialogs, fake installer | `test_port` |
 | Truth and native export | synthetic + cached originals | `test_export_counts`, `test_export_native_layer`, `test_export_report`, `test_exporters`, `test_truth_data_dir_readers`, `test_truth_diff`, `test_truth_layout` |
 | Scrapers, upstream and provenance | inline sources, synthetic | `test_check_freshness`, `test_dedup`, `test_elec_scrapers`, `test_fbneo_parser`, `test_find_pinned_revision`, `test_hash_merge`, `test_launchers`, `test_launchers_emudeck`, `test_launchers_recalbox`, `test_launchers_retrobat`, `test_launchers_retrodeck`, `test_launchers_retropie`, `test_launchers_rocknix`, `test_mame_devices`, `test_mame_parser`, `test_mame_ref_audit`, `test_profile_sync`, `test_provenance`, `test_refresh_data_dirs`, `test_refresh_failures`, `test_refresh_stale`, `test_retrodeck_scraper_errors`, `test_romset_recipes`, `test_scraper_contract`, `test_upstream`, `test_upstream_index` |
-| Site, docs and repository contracts | rendered pages, sources | `test_contributing_text`, `test_coverage_cache`, `test_data_dir_refs`, `test_dataclass_defaults`, `test_doc_pages`, `test_doc_surfaces`, `test_optional_dependencies`, `test_prose_style`, `test_schema_semantic_gate`, `test_site_availability`, `test_site_content_data`, `test_site_copy`, `test_site_cores`, `test_site_emulator_page`, `test_site_exports`, `test_site_funnel`, `test_site_images`, `test_site_picker`, `test_site_platform_hashes`, `test_site_r2_p0`, `test_site_render`, `test_site_system_links`, `test_site_validation`, `test_site_weight`, `test_site_write`, `test_validate_pr`, `test_validate_pr_flow`, `test_validate_pr_hashes`, `test_workflow_paths` |
+| Site, docs and repository contracts | rendered pages, sources | `test_contributing_text`, `test_coverage_cache`, `test_data_dir_refs`, `test_dataclass_defaults`, `test_doc_pages`, `test_doc_surfaces`, `test_optional_dependencies`, `test_prose_style`, `test_schema_semantic_gate`, `test_site_availability`, `test_site_content_data`, `test_site_copy`, `test_site_cores`, `test_site_emulator_page`, `test_site_exports`, `test_site_funnel`, `test_site_images`, `test_site_picker`, `test_site_platform_hashes`, `test_site_r2_p0`, `test_site_r2_wiki`, `test_site_render`, `test_site_system_links`, `test_site_validation`, `test_site_weight`, `test_site_write`, `test_validate_pr`, `test_validate_pr_flow`, `test_validate_pr_hashes`, `test_workflow_paths` |
 
 ## Test architecture
 
@@ -398,11 +397,12 @@ nav_title: Save files    # only when the menu names it otherwise than its headin
   two without renumbering. The generated pages (systems, emulators, the gaps
   and data pages) hold fixed places among them, set in `generate_nav`.
 - `nav_title` is the menu label. Without it the menu shows the page's `# `
-  heading. It is not `title`, which both MkDocs and Astro Starlight read as
-  the page's own title.
+  heading, which is the rule: a page keeps one name in the menu, its heading
+  and the links to it. It is not `title`, which both MkDocs and Astro
+  Starlight read as the page's own title.
+- `group` places a Reference page under a group of that tab, such as
+  `Checking files` or `Data`.
 - `nav: false` keeps a page out of the menu on purpose.
-  `getting-started.md` does, since it only links the pages that took its
-  content.
 
 `python scripts/generate_site.py` stops with the page's name when `level` or
 `order` is missing, or when two pages of a tab take the same `order`.