Release 1.0.4: slow the pub.dev demo GIF

[omar-hanafy]

Summary

• doubles the README demo GIF duration from 11 to 22 seconds
• preserves all 88 frames, the infinite loop, and the 360 by 546 dimensions
• reduces the GIF slightly from 3,070,034 to 3,031,414 bytes
• synchronizes package, example, website metadata, and assistant-plugin versions at 1.0.4

Validation

• GIF timing and structure validation
• dart format check
• flutter analyze
• flutter test: 100 passed
• example flutter test: 11 passed
• AI plugin validation
• Wasm Pages build
• flutter pub publish --dry-run: 0 warnings
• Pana 0.23.14: 160/160