legal: add LICENSE, ATTRIBUTION.md, and CSS snippet headers

- Add MIT LICENSE file (was declared but missing)
- Add ATTRIBUTION.md crediting Karpathy, Nate Herk, SlRvb, and bundled plugins
- Add GPL-2.0 attribution headers to ITS-Dataview-Cards.css and ITS-Image-Adjustments.css

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

ATTRIBUTION.md

@@ -0,0 +1,55 @@
+# Attributions
+
+cosmic-brain is an original work. The following third-party patterns, tools, and creators informed its design.
+
+---
+
+## LLM Wiki Pattern
+
+**Author:** Andrej Karpathy
+**Source:** https://github.com/karpathy
+**Use:** The core architecture of cosmic-brain — using an LLM to build and maintain a structured wiki from raw sources — is based on the LLM Wiki pattern Karpathy described publicly. cosmic-brain is an independent implementation; no code or content from Karpathy's repositories was copied.
+
+---
+
+## Hot Cache & Cross-Project Patterns
+
+**Author:** Nate Herk
+**Channel:** https://youtube.com/@nateherk
+**Use:** The hot cache pattern (a rolling ~500-word context summary) and cross-project vault referencing were demonstrated by Nate Herk. cosmic-brain implements these patterns independently. No transcript or video content is included in this repository.
+
+---
+
+## ITS CSS Snippets
+
+**Author:** SlRvb
+**Source:** https://github.com/SlRvb/Obsidian--ITS-Theme
+**License:** GPL-2.0
+**Files:**
+- `.obsidian/snippets/ITS-Dataview-Cards.css`
+- `.obsidian/snippets/ITS-Image-Adjustments.css`
+
+These snippets are distributed under the GPL-2.0 license. Per GPL-2.0 terms, any modifications to these files must also be released under GPL-2.0.
+
+---
+
+## Obsidian Plugins (pre-installed)
+
+The following Obsidian community plugins ship with this vault as pre-installed binaries. They are the property of their respective authors and are distributed here solely to reduce setup friction. Users should verify license terms via each plugin's repository.
+
+| Plugin | Author | Repository |
+|--------|--------|-----------|
+| Calendar | Liam Cain | https://github.com/liamcain/obsidian-calendar-plugin |
+| Thino | Boninall (Quorafind) | https://github.com/Quorafind/Obsidian-Thino |
+| Obsidian Excalidraw | Zsolt Viczian | https://github.com/zsviczian/obsidian-excalidraw-plugin |
+| Obsidian Banners | Danny Hernandez | https://github.com/noatpad/obsidian-banners |
+
+`obsidian-excalidraw-plugin/main.js` is **not** included in this repository. It is downloaded automatically by `bin/setup-vault.sh` from the plugin's official GitHub releases.
+
+---
+
+## cosmic-brain
+
+**Author:** AgriciDaniel / AI Marketing Hub
+**License:** MIT (see [LICENSE](LICENSE))
+**Repository:** https://github.com/AgriciDaniel/cosmic-brain