Fix README rendering and sync setup/deployment docs with repository

[meva]

Motivation

• Fix broken markdown fencing so the “Build for Production” and “Deployment” sections render correctly.
• Ensure documented scripts and paths match the actual repository to avoid confusion during setup and deployment.
• Add a small maintainer checklist to reduce documentation drift after future refactors.

Description

• Repaired the code-fence and layout around the Build for Production and Deployment sections so code blocks render as intended.
• Updated setup/build/deployment instructions to reflect actual scripts in package.json and existing helper script, including dev, build, build:web, preview, start, and ./prepare-dist.sh.
• Corrected the clone/cd example to git clone https://github.com/<your-org>/FiscalSunset.git and cd FiscalSunset.
• Reconciled the Project Structure tree to match real paths (added public/Images/, assets/images/, prepare-dist.sh, metadata.json, etc., and removed outdated entries).
• Added a Docs Sanity Checklist section with concrete steps to validate README scripts and paths after refactors.

Testing

• Verified documented npm run ... commands in the README exist in package.json scripts using a script-based extraction check, and the check succeeded.
• Verified that all paths listed in the updated Project Structure exist in the repository using an automated path-existence check, and the check succeeded.
• Attempted a GitHub-style markdown render with npx cmark-gfm README.md > /tmp/README.gfm.html, but the run failed due to the environment's npm registry policy (403 Forbidden), so a local preview could not be produced in this environment.

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Codex Task