docs: Update Phase 0 with specific test fix requirements

Per ADR-012, Phase 0 now specifies:
- 5 tests to REMOVE (broken multiprocessing)
- 4 tests to FIX (brittle assertions)
- 1 test to RENAME (misleading name)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

starpunk/routes/public.py

@@ -116,7 +116,10 @@ def _generate_feed_with_cache(format_name: str, non_streaming_generator):
             limit=max_items,
         )
 
-        response = Response(content, mimetype=get_mime_type(format_name))
+        # Create response with proper Content-Type including charset
+        mime_type = get_mime_type(format_name)
+        content_type = f"{mime_type}; charset=utf-8"
+        response = Response(content, content_type=content_type)
         response.headers["Cache-Control"] = f"public, max-age={cache_seconds}"
         return response
 
@@ -141,7 +144,9 @@ def _generate_feed_with_cache(format_name: str, non_streaming_generator):
             return response
 
         # Return cached content with ETag
-        response = Response(content, mimetype=get_mime_type(format_name))
+        mime_type = get_mime_type(format_name)
+        content_type = f"{mime_type}; charset=utf-8"
+        response = Response(content, content_type=content_type)
         response.headers["ETag"] = etag
         cache_seconds = current_app.config.get("FEED_CACHE_SECONDS", 300)
         response.headers["Cache-Control"] = f"public, max-age={cache_seconds}"
@@ -163,7 +168,9 @@ def _generate_feed_with_cache(format_name: str, non_streaming_generator):
     etag = feed_cache.set(format_name, content, notes_checksum)
 
     # Return fresh content with ETag
-    response = Response(content, mimetype=get_mime_type(format_name))
+    mime_type = get_mime_type(format_name)
+    content_type = f"{mime_type}; charset=utf-8"
+    response = Response(content, content_type=content_type)
     response.headers["ETag"] = etag
     cache_seconds = current_app.config.get("FEED_CACHE_SECONDS", 300)
     response.headers["Cache-Control"] = f"public, max-age={cache_seconds}"