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/images/logo-dark.svg

@@ -0,0 +1,6 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="140" height="32" viewBox="0 0 140 32" fill="none">
+  <g stroke-linecap="round" stroke-linejoin="round">
+    <path stroke="#e4e4e7" stroke-width="2" d="m18 4-8.414 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"/>
+  </g>
+  <text x="32" y="22" font-family="system-ui, -apple-system, sans-serif" font-size="18" font-weight="600" fill="#e4e4e7">Paperclip</text>
+</svg>

docs/images/logo-light.svg

@@ -0,0 +1,6 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="140" height="32" viewBox="0 0 140 32" fill="none">
+  <g stroke-linecap="round" stroke-linejoin="round">
+    <path stroke="#18181b" stroke-width="2" d="m18 4-8.414 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"/>
+  </g>
+  <text x="32" y="22" font-family="system-ui, -apple-system, sans-serif" font-size="18" font-weight="600" fill="#18181b">Paperclip</text>
+</svg>