Document the early-exit and settlement UI flows and align README "In Progress" feature status

[1nonlypiece]

📌 Description

The README still marks Wallet Integration as "In Progress" and lists features at
a high level, while the codebase has shipped detailed settlement and early-exit
surfaces (src/components/modals/SettlementModal.tsx,
CommitmentEarlyExitModal/) backed by real endpoints
(settle, settle/preview, early-exit, early-exit/preview). There is
test-settle.md and test-auth.md scratch content but no consolidated user-flow
documentation for settlement and early exit.

This issue adds a settlement/early-exit flow doc and reconciles README feature
status.

Goal: a single, accurate doc describing the settlement and early-exit UI
flows (states, endpoints, error reasons), with README status updated to match
reality.

🎯 Requirements and Context

• Document settlement states (eligible/ineligible reasons, settled) and the
  endpoints they consume, referencing getSettlementIneligibleReasonCopy.
• Document the early-exit flow, including the penalty-free grace period and the
  type-to-confirm safeguard.
• Update README "Features" / Wallet Integration status to reflect current state.
• Cross-link from README and DEVELOPER_GUIDE.md.

🛠️ Suggested Execution

1. Create a branch

git checkout -b feature/settlement-early-exit-docs

2. Implement changes

• Add docs/settlement-and-early-exit-flows.md.
• Update README.md feature status and link the new doc.
• Fold any still-relevant notes from test-settle.md into the doc.

3. Test and commit

• Validate links (validate-openapi.sh is unrelated, but check markdown links).
• Ensure code references (file paths, endpoint paths) are accurate.

Example commit message

docs: settlement and early-exit UI flow documentation; sync README status

✅ Guidelines

• Minimum 95% test coverage is N/A for docs, but include verifiable,
  accurate references; keep docs clear and complete.
• Timeframe: 96 hours.

🏷️ Labels

type-documentation · area-frontend · MAYBE REWARDED · GRANTFOX OSS · OFFICIAL CAMPAIGN

💬 Community & Support

• Join the CommitLabs contributor Discord: https://discord.gg/WV7tdYkJk
• Introduce yourself before starting to avoid duplicate work.
• Maintainers triage actively and review fast.

[Errordog2]

/attempt #599

PR: #612

Submitted docs coverage for the settlement and early-exit UI flows:

• new docs/settlement-and-early-exit-flows.md
• README feature/status update and doc link
• DEVELOPER_GUIDE cross-link for future API/modal changes

Validation: verified the new doc exists on the branch and both README/DEVELOPER_GUIDE link to it.