docs: add DeepWiki badge to README

[roottool]

Description

Add DeepWiki badge to README for AI-powered codebase documentation and Q&A.

Type of Change

• Bug fix (non-breaking change fixing an issue)
• Security fix (non-breaking change addressing a security issue)
• Documentation (changes to documentation only)
• Refactoring (non-breaking change improving code structure)
• Tests (adding or updating tests)
• Tooling / CI (changes to build tools, CI configuration)

Boundary Checklist (Required for Implementation Changes)

safe-formdata enforces a strict trust boundary for FormData.
If any item below does not apply, this change likely does not belong here.

For documentation, tooling, or CI changes: You may skip this section by checking the box below and explaining why.

• This is a non-implementation change (Documentation, Tooling, or CI only)
  • Reason: Adding a documentation badge only, no code changes

Security & API Stability

Security Impact:

• No impact on security (no changes to forbidden keys, prototype safety)
• Reviewed against security rules in AGENTS.md
• If security-related: Explain impact and mitigation

API Contract:

• No changes to public API (parse function signature, type definitions)
• No breaking changes to ParseResult, ParseIssue, or IssueCode
• If API change: Is this a breaking change? (Yes/No + explanation)

Versioning:

• Change is compatible with current v0.x versioning policy
• If breaking change proposed: Justification for major version bump

Testing

Automated Checks:

• TypeScript type checking passes (bun run check:type:source)
• All tests pass (bun run test)
• Build succeeds (bun run build)

Additional Verification:

No additional testing required - documentation-only change (badge addition).

---

🤖 Generated with Claude Code

Co-Authored-By: Claude noreply@anthropic.com

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (4bed3b0) to head (f05454a).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #50   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            3         3           
  Lines           22        22           
  Branches         6         6           
=========================================
  Hits            22        22           

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