fix(learn): fix workshop progress bar calculation and deduplicate cha…

[rohanesor]

Fixes #1785

Description

Fixes an issue where workshops and labs (e.g. in JS and Python certs) display incorrect progress (adding 10% per step instead of 20%) and only reach 50% completion when all steps are finished.

Motivation & Context

Block.fromJson parsed data['challengeOrder'] without deduplicating challenge IDs. When duplicate challenge entries existed in block metadata, block.challenges.length became double the actual step count (e.g. 10 instead of 5), while user progress only records 1 completion per unique challenge ID (e.g. 5). Thus 5 / 10 = 50%.

Changes Made

• mobile-app/lib/models/learn/curriculum_model.dart: Deduplicated challengeOrder by id in Block.fromJson to ensure challenges and challengeTiles contain accurate unique step counts.
• mobile-app/lib/ui/views/learn/widgets/pass/pass_widget_view.dart: Added .clamp(0.0, 1.0) and .clamp(0, 100) bounds safety to progress indicators.

Checklist

• Verified progress calculation logic.
• Follows existing project architecture and conventions.
• Clean minimal changes across 2 files.