docs: standardize UI terminology to use "view" consistently (#325)

* docs: standardize UI terminology to use "view" consistently

Replaces "widget" and "Guest UI" terminology with "view" across
the codebase as decided in the community survey.

This change updates:
- Specification document
- SDK source code and JSDoc comments
- Example servers and documentation
- Plugin documentation and skills

Closes #71

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/e2e/servers.spec.ts

@@ -38,7 +38,7 @@ const SLOW_SERVERS: Record<string, number> = {
 
 // Servers to skip in CI (require special resources like GPU, large ML models)
 const SKIP_SERVERS = new Set<string>([
-  // None currently - say-server widget works without TTS model for screenshots
+  // None currently - say-server view works without TTS model for screenshots
 ]);
 
 // Optional: filter to a single example via EXAMPLE env var (folder name)