Add Ruby and Swift detection to selfmodel.sh adapt

[VictorVVedtion]

Description

selfmodel.sh adapt auto-detects tech stacks but is missing Ruby and Swift support.

What to do

In scripts/selfmodel.sh, find the detect_stack() function and add detection for:

• Ruby: check for Gemfile, *.rb files, Rails (config/routes.rb)
• Swift: check for Package.swift, *.swift files, Xcode project (*.xcodeproj)

Follow the existing pattern used for Go, Rust, and Python detection.

Files to modify

• scripts/selfmodel.sh — detect_stack() function

Acceptance criteria

• selfmodel.sh adapt detects Ruby projects correctly
• selfmodel.sh adapt detects Swift projects correctly
• Existing detections still work (no regressions)