✨ Add project detail page with prev/next navigation (Story 2.3)

- Enhance ProjectController show() with prev/next navigation data
- Create useFetchProject composable with ProjectNavigation type
- Implement [slug].vue with full project details:
  - Hero image, title with featured badge, formatted date
  - Description, external links (site/GitHub)
  - Skills grid with level progression (before → after)
  - Prev/next navigation with project titles
  - 404 state with spider narrator
- Add dynamic SEO meta tags with og:image from project
- Responsive design: stacked mobile, grid desktop

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/app/composables/useFetchProject.ts

@@ -0,0 +1,33 @@
+import type { Project } from '~/types/project'
+
+export interface ProjectNavigation {
+  prev: { slug: string; title: string } | null
+  next: { slug: string; title: string } | null
+}
+
+interface ProjectResponse {
+  data: Project
+  meta: { lang: string }
+  navigation: ProjectNavigation
+}
+
+interface ProjectError {
+  error: {
+    code: string
+    message: string
+  }
+}
+
+export function useFetchProject(slug: string | Ref<string>) {
+  const config = useRuntimeConfig()
+  const { locale } = useI18n()
+  const slugValue = toValue(slug)
+
+  return useFetch<ProjectResponse, ProjectError>(`/projects/${slugValue}`, {
+    baseURL: config.public.apiUrl as string,
+    headers: {
+      'X-API-Key': config.public.apiKey as string,
+      'Accept-Language': locale.value,
+    },
+  })
+}