docs: lowercase internal docs + migrate website docs to public-docs/ (#634)

* docs: rename to lowercase + drop leftover plans

Rename docs in docs/ to lowercase kebab-case for consistency and update
all references in CLAUDE.md, CONTRIBUTING.md, CHANGELOG.md,
packages/server/CLAUDE.md, and inter-doc links.

Drop two leftover design plan docs:
- docs/ATTACHMENT_BASED_REVIEW_CONTEXT_PLAN.md
- docs/plan-approval-normalization.md

* docs: drop stale uppercase entries from case-insensitive rename

* feat(website): power /docs from public-docs/ markdown tree

Move website docs out of TSX route components and into a root-level
public-docs/ directory of plain markdown files with frontmatter
(title, description, nav, order).

- Add packages/website/src/docs.ts loader using import.meta.glob with
  ?raw to compile the markdown into the bundle at build time.
- Replace the 9 hand-written docs/*.tsx routes with a single $.tsx
  catch-all that renders any slug via react-markdown.
- Drive the docs sidebar nav from frontmatter order/nav.
- Auto-discover docs routes in vite.config.ts so the sitemap stays in
  sync without manual edits.

* fix(website): bind dev server to 0.0.0.0 so port collisions trigger fallback

`host: "127.0.0.1"` (or unset) lets macOS coexist with another process
holding an IPv6 dual-stack `*:8082` socket, so Vite never sees
EADDRINUSE and silently binds alongside it. Forcing IPv4 wildcard
makes the conflict real, and Vite's default `strictPort: false`
falls through to the next free port.

* fix(website): restore docs page styling after markdown migration

Add a .docs-prose class that mirrors the styling the original
docs/*.tsx components hand-rolled (h1/h2/h3 sizes, paragraph/list
spacing, link colors, code blocks, callout-style blockquotes).

ReactMarkdown was emitting unstyled HTML because the previous
wrapper class only had inline-code rules — headings and code
blocks fell back to user-agent defaults.

packages/website/src/docs.ts

@@ -0,0 +1,81 @@
+interface DocFrontmatter {
+  title: string;
+  description: string;
+  nav: string;
+  order: number;
+}
+
+export interface Doc {
+  slug: string;
+  href: string;
+  frontmatter: DocFrontmatter;
+  content: string;
+}
+
+function parseFrontmatter(raw: string): { data: Record<string, string>; content: string } {
+  const match = raw.match(/^---\r?\n([\s\S]*?)\r?\n---\r?\n?([\s\S]*)$/);
+  if (!match) return { data: {}, content: raw };
+
+  const data: Record<string, string> = {};
+  for (const line of match[1].split("\n")) {
+    const colonIdx = line.indexOf(":");
+    if (colonIdx === -1) continue;
+    const key = line.slice(0, colonIdx).trim();
+    const value = line
+      .slice(colonIdx + 1)
+      .trim()
+      .replace(/^["']|["']$/g, "");
+    data[key] = value;
+  }
+
+  return { data, content: match[2] };
+}
+
+const docModules = import.meta.glob("../../../public-docs/**/*.md", {
+  eager: true,
+  query: "?raw",
+  import: "default",
+}) as Record<string, string>;
+
+function pathToSlug(path: string): string {
+  const after = path.split("/public-docs/")[1] ?? path;
+  const noExt = after.replace(/\.md$/, "");
+  return noExt === "index" ? "" : noExt;
+}
+
+function loadDocs(): Doc[] {
+  const docs: Doc[] = [];
+
+  for (const [path, raw] of Object.entries(docModules)) {
+    const { data, content } = parseFrontmatter(raw);
+    const slug = pathToSlug(path);
+    const href = slug === "" ? "/docs" : `/docs/${slug}`;
+    const order = Number.parseInt(data.order ?? "999", 10);
+
+    docs.push({
+      slug,
+      href,
+      frontmatter: {
+        title: data.title ?? "",
+        description: data.description ?? "",
+        nav: data.nav ?? data.title ?? slug,
+        order: Number.isFinite(order) ? order : 999,
+      },
+      content,
+    });
+  }
+
+  docs.sort((a, b) => a.frontmatter.order - b.frontmatter.order);
+  return docs;
+}
+
+let cached: Doc[] | undefined;
+
+export function getDocs(): Doc[] {
+  if (!cached) cached = loadDocs();
+  return cached;
+}
+
+export function getDoc(slug: string): Doc | undefined {
+  return getDocs().find((d) => d.slug === slug);
+}