Add the curated Learning sources (#6)

Fifteen English Learning sources join ByteByteGo in the catalog: System
Design One, The Pragmatic Engineer (blog), Martin Fowler, Julia Evans,
Dan Luu, The Cloudflare Blog, Netflix Technology Blog, Engineering at
Meta, GitHub Blog: Engineering, Latent Space, Import AI, Interconnects,
Ahead of AI and Lilian Weng (on by default), and InfoQ (off).

Tests pin the Learning catalog, check that existing installs get the
new on-by-default Sources and that the Learn tab shows their posts from
the last 14 days. A live test times a full refresh. The README gets a
Learn feature bullet and a Learning sources table.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lib/data/default_sources.dart

@@ -212,6 +212,155 @@ const defaultSources = <NewsSource>[
     description: 'System design explained with diagrams',
     enabledByDefault: true,
   ),
+  NewsSource(
+    id: 'systemdesignone',
+    name: 'System Design One',
+    feedUrl: 'https://newsletter.systemdesign.one/feed',
+    homepage: 'https://newsletter.systemdesign.one',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'System design case studies of real systems',
+    enabledByDefault: true,
+  ),
+  NewsSource(
+    id: 'pragmaticengineer-blog',
+    name: 'The Pragmatic Engineer (blog)',
+    feedUrl: 'https://blog.pragmaticengineer.com/rss/',
+    homepage: 'https://blog.pragmaticengineer.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'How big tech and startups build software (free posts)',
+    enabledByDefault: true,
+  ),
+  NewsSource(
+    id: 'martinfowler',
+    name: 'Martin Fowler',
+    feedUrl: 'https://martinfowler.com/feed.atom',
+    homepage: 'https://martinfowler.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Software architecture, refactoring, delivery practices',
+    enabledByDefault: true,
+  ),
+  NewsSource(
+    id: 'juliaevans',
+    name: 'Julia Evans',
+    feedUrl: 'https://jvns.ca/atom.xml',
+    homepage: 'https://jvns.ca',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Systems, networking and Unix tools, explained plainly',
+    enabledByDefault: true,
+  ),
+  NewsSource(
+    id: 'danluu',
+    name: 'Dan Luu',
+    feedUrl: 'https://danluu.com/atom.xml',
+    homepage: 'https://danluu.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Long, data-driven essays on computers and engineering',
+    enabledByDefault: true,
+  ),
+  NewsSource(
+    id: 'cloudflare-blog',
+    name: 'The Cloudflare Blog',
+    feedUrl: 'https://blog.cloudflare.com/rss/',
+    homepage: 'https://blog.cloudflare.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Networking, security and incident write-ups in depth',
+    enabledByDefault: true,
+  ),
+  NewsSource(
+    id: 'netflix-techblog',
+    name: 'Netflix Technology Blog',
+    feedUrl: 'https://netflixtechblog.com/feed',
+    homepage: 'https://netflixtechblog.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Distributed systems, data and streaming at scale',
+    enabledByDefault: true,
+  ),
+  NewsSource(
+    id: 'meta-engineering',
+    name: 'Engineering at Meta',
+    feedUrl: 'https://engineering.fb.com/feed/',
+    homepage: 'https://engineering.fb.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Infrastructure, AI and production engineering at Meta',
+    enabledByDefault: true,
+  ),
+  NewsSource(
+    id: 'github-engineering',
+    name: 'GitHub Blog: Engineering',
+    feedUrl: 'https://github.blog/engineering/feed/',
+    homepage: 'https://github.blog/engineering/',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'How GitHub builds and runs GitHub',
+    enabledByDefault: true,
+  ),
+  NewsSource(
+    id: 'latent-space',
+    name: 'Latent Space',
+    feedUrl: 'https://www.latent.space/feed',
+    homepage: 'https://www.latent.space',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'AI engineering: interviews and deep dives',
+    enabledByDefault: true,
+  ),
+  NewsSource(
+    id: 'import-ai',
+    name: 'Import AI',
+    feedUrl: 'https://importai.substack.com/feed',
+    homepage: 'https://importai.substack.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Weekly AI research digest by Jack Clark',
+    enabledByDefault: true,
+  ),
+  NewsSource(
+    id: 'interconnects',
+    name: 'Interconnects',
+    feedUrl: 'https://www.interconnects.ai/feed',
+    homepage: 'https://www.interconnects.ai',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Language model training and research, analysed',
+    enabledByDefault: true,
+  ),
+  NewsSource(
+    id: 'ahead-of-ai',
+    name: 'Ahead of AI',
+    feedUrl: 'https://magazine.sebastianraschka.com/feed',
+    homepage: 'https://magazine.sebastianraschka.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'LLM research explained, by Sebastian Raschka',
+    enabledByDefault: true,
+  ),
+  NewsSource(
+    id: 'lilianweng',
+    name: 'Lilian Weng',
+    feedUrl: 'https://lilianweng.github.io/index.xml',
+    homepage: 'https://lilianweng.github.io',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Thorough surveys of machine learning topics',
+    enabledByDefault: true,
+  ),
+  NewsSource(
+    id: 'infoq',
+    name: 'InfoQ',
+    feedUrl: 'https://feed.infoq.com/',
+    homepage: 'https://www.infoq.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Software architecture and engineering talks, high volume',
+  ),
 ];
 
 /// The curated sources before the app remembered which ones it had seen.