Doug/improve default sast ruleset

[dacoburn]

Description

This PR improves the Socket Basics SAST ruleset defaults and updates documentation to reflect the current state of the project:

SAST Ruleset Improvements

• Reduced false positives across all language rulesets (Python, JavaScript/TypeScript, Java, PHP, Ruby, Go, Kotlin, Scala, Swift, Rust, C/C++, .NET, Elixir, Erlang, Objective-C)
• Enhanced rule patterns with more precise detection logic and better context-awareness
• Expanded Python ruleset significantly (~1,200 lines added) with comprehensive security patterns
• Improved JavaScript/TypeScript detection (~580 lines) with better framework-specific patterns
• Enhanced Java and PHP rulesets with additional vulnerability patterns and reduced noise
• Updated default enabled rules in connectors.yaml to focus on high-confidence, actionable findings

Documentation Updates

• Replaced all Semgrep references with OpenGrep - the actual SAST engine used by Socket Basics
• Corrected installation instructions - Socket Basics is not published to PyPI and must be installed from source using pip install -e .
• Added OpenGrep installation guide with official installer command
• Updated installation documentation across local-installation.md, local-install-docker.md, pre-commit-hook.md, and github-action.md

Other Changes

• Added vulnerable app test submodules (govwa, play-webgoat) to .gitmodules
• Updated .gitignore for better Python development workflow
• Version bump to reflect ruleset improvements

Public Changelog

• Improved SAST ruleset quality with reduced false positives and enhanced detection patterns across all supported languages
• Expanded Python and JavaScript/TypeScript security rules with more comprehensive vulnerability coverage
• Updated default enabled rules to focus on high-confidence, actionable security findings