refactor: split out docs/manual routes from shared MdxRoute file

[jderochervlk]

• Add DocsManualRoute for /docs/manual pages with sidebar and TOC
• Implement SidebarHelpers for sidebar nav/category generation
• Add MdxFile.loadAllAttributes for loading manual doc frontmatter
• Update routes to support manual docs and exclude from mdxRoutes
• Document commit/PR conventions in AGENTS.md

[Copilot]

Pull request overview

Refactors routing so /docs/manual/* pages are served by a dedicated DocsManualRoute (with sidebar + TOC), and introduces shared helpers/utilities to support manual doc navigation.

Changes:

• Add DocsManualRoute to load/compile manual MDX, build sidebar categories, and generate a per-page table of contents.
• Introduce SidebarHelpers and MdxFile.loadAllAttributes to generate sidebar nav data from MDX frontmatter.
• Update route configuration to include manual docs routes and exclude them from the shared mdxRoutes; document PR/commit conventions in AGENTS.md.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/SidebarHelpers.resi	Exposes sidebar helper function signatures for nav/category construction.
src/SidebarHelpers.res	Implements sidebar nav item conversion and grouped category helpers.
src/MdxFile.resi	Adds public API for loadAllAttributes to scan MDX frontmatter.
src/MdxFile.res	Implements loadAllAttributes and refactors resolveFilePath formatting.
app/routes/DocsManualRoute.resi	Declares loader data contract for manual docs route.
app/routes/DocsManualRoute.res	New manual-docs route: compiles MDX, builds sidebar + TOC, renders layout.
app/routes.res	Registers manual-docs routes and filters them out of mdxRoutes.
AGENTS.md	Adds guidance for commit/PR conventions.

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