refactor: shorten lesson titles and improve content

- Shorten verbose lesson titles for better sidebar display
- Minor content improvements across lessons

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

lessons/24-html-progress-meter.json

@@ -1,7 +1,7 @@
 {
 	"$schema": "../schemas/code-crispies-module-schema.json",
 	"id": "html-progress-meter",
-	"title": "Progress & Meter Elements",
+	"title": "Progress/Meter",
 	"description": "Display completion status and scalar measurements natively",
 	"mode": "html",
 	"difficulty": "beginner",