🏗️ Add Ralph Wiggum long-running agent loop script

[Miyamura80]

Summary

• Added scripts/ralph.sh, a long-running AI agent loop script.
• Modified the script to use opencode as the default tool.
• Added "Ralph Wiggum Agent Loop" to the features table in README.md.

[greptile-apps]

Greptile Overview

Greptile Summary

This PR adds Ralph Wiggum, an autonomous AI agent loop system for iterative code development. The implementation includes:

• Core script (scripts/ralph.sh): Orchestrates the agent loop with support for multiple AI tools (opencode, amp, claude). Previous review comments about missing file checks have been addressed.
• Agent instructions (scripts/ralph/prompt.md): Comprehensive guidance for the autonomous agent, including task execution, progress tracking, and quality requirements.
• Two new Claude skills: PRD generation (prd) and PRD-to-JSON conversion (ralph) for structured task management.
• Integration: Makefile target with appropriate safety warnings and dependency checks (jq).
• Documentation: README updated to reflect the new feature availability.

The implementation follows the repository's conventions for commit messages (🏗️ emoji for initial implementation), script structure, and includes proper dependency validation.

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• All previously identified issues have been addressed. The script includes proper error handling, file existence checks, dependency validation, and safety warnings. The implementation is well-documented and follows repository conventions.
• No files require special attention

Important Files Changed

Filename	Overview
scripts/ralph.sh	Main Ralph agent loop script. Previous comments addressed with file checks for prompt.md.
scripts/ralph/prompt.md	Agent instructions for Ralph. Clear, comprehensive guidance for autonomous coding iterations.
.claude/skills/ralph/SKILL.md	Skill documentation for converting PRDs to Ralph's JSON format. Well-structured with good examples.
.claude/skills/prd/SKILL.md	PRD generation skill with clear templates and examples. Good guidance on writing actionable requirements.
Makefile	Added ralph target with appropriate warnings and dependency checks. Good integration with existing patterns.

[greptile-apps]

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[greptile-apps]

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