refactor: fix all compiler warnings

[pwltr]

Description

Resolve all Swift compiler warnings:

• Update deprecated onChange(of:perform:) usages to new two/zero-parameter APIs (iOS 17+)
• Resolve Swift 6 actor isolation and concurrency warnings in view models and services
• Fix unused bindings/results and unreachable catch blocks
• Add proper inputs/outputs to “Remove Static Framework Stubs” run script to avoid always-run warning

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.