fix: restore docs deleted in v0.2.3 release, add Paperclip branding

- Restored docs/ directory that was accidentally deleted by `git add -A`
  in the v0.2.3 release script
- Replaced generic "P" favicon with actual paperclip icon using brand
  primary color (#2563EB)
- Added light/dark logo SVGs for Mintlify navbar (paperclip icon + wordmark)
- Updated docs.json with logo configuration for dark/light mode
- Fixed release.sh to stage only release-related files instead of `git add -A`
  to prevent sweeping unrelated changes into release commits

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/favicon.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="-4 -4 32 32" fill="none" stroke-linecap="round" stroke-linejoin="round">
+  <rect x="-4" y="-4" width="32" height="32" rx="6" fill="#2563EB"/>
+  <path stroke="#ffffff" stroke-width="2" d="m16 6-8.414 8.586a2 2 0 0 0 2.829 2.829l8.414-8.586a4 4 0 1 0-5.657-5.657l-8.379 8.551a6 6 0 1 0 8.485 8.485l8.379-8.551"/>
+</svg>