docs: clarify Ralph runner setup and output paths

[txhno]

Summary

• clarify in the README that copying ralph.sh into the project is required and marketplace/global skill installs are optional helpers, not a full alternative
• document that prd.json and progress.txt must live alongside ralph.sh
• update the /ralph and /prd skill docs so generated outputs point to the correct project-local paths

Validation

• reviewed README and skill diffs for consistent setup and path guidance
• git diff --check

Closes #125

Also addresses the setup confusion described in #99.

[RahulLanjewar93]

@snarktank any eta when this can be merged? the issue seems valid and this pr does look good to solve the issue
@txhno thanks for the PR mate

[dosentmatter]

Maybe should just start an improved fork. This repo has 20k stars but only 20 commits and last commit was 4 months ago.

It seems like the setup is terribly manual. Right now, first time user has to install prerequisite dependencies, install the skills, copy the ralph.sh, make it executable, run 2 skills to get prd then prd.json, then finally run ralph.sh. Which doesn't make sense in the age of AI coding agents.

I think it should be automated as much as possible with one time installs with updates and quick setup for each run on a repo. The ralph binary can be installed on PATH and dependencies managed with a package manager. Maybe have a setup script that installs the skills with https://www.npmjs.com/package/skills. Not sure if the /prd and /ralph skills can be combined into a single step. Or if the whole flow can just be started from shell without manually triggering the skills.

Maybe someone should just run ralph on this ralph repo itself to improve the developer experience.