chore: more cleanup in the specs

specs/generation.allium

@@ -49,6 +49,20 @@ entity SiteGeneration {
     generated_files: GeneratedFile with project_id = this.project_id
 }
 
+surface GenerationStatusSurface {
+    context generation: SiteGeneration
+
+    exposes:
+        generation.project_id
+        generation.base_url
+        generation.language
+        generation.blog_languages
+        generation.max_posts_per_page
+        generation.pico_theme
+        generation.sections
+        generation.generated_files.count
+}
+
 invariant IncrementalByContentHash {
     -- Files are only written when content_hash changes
     -- generatedFileHashes table tracks (projectId, relativePath, contentHash)
@@ -61,6 +75,21 @@ invariant MultiLanguageRoutes {
     -- Each language subtree gets its own feeds and archives
 }
 
+invariant CanonicalBaseUrlConfigured {
+    for generation in SiteGenerations:
+        generation.base_url != ""
+}
+
+invariant NamedPicoTheme {
+    for generation in SiteGenerations where generation.pico_theme != null:
+        generation.pico_theme != ""
+}
+
+invariant GeneratedFilesTracked {
+    for generation in SiteGenerations:
+        generation.generated_files.count >= 0
+}
+
 -- Core section: root pages, sitemap, RSS, Atom, calendar.json
 
 rule GenerateCoreSectionPages {