refactor: inline src/issues into parse.ts and remove issues directory

[roottool]

Description

Refactoring to remove the src/issues/ directory and inline its contents into parse.ts.

• Remove the createIssue helper function and inline issue object literals at each call site in parse.ts
• Move the FORBIDDEN_KEYS constant (internal, unexported) into parse.ts
• Delete the src/issues/ directory (forbiddenKeys.ts / forbiddenKeys.test.ts / createIssue.ts / createIssue.test.ts)

Rationale

• FORBIDDEN_KEYS is an internal constant not exported from index.ts; its only consumer is parse.ts
• The coverage provided by forbiddenKeys.test.ts (checking that the set contains 3 values) is already covered behaviorally by the forbidden_key cases in parse.test.ts
• The dedicated folder and dedicated tests were structural overhead not warranted by the size of the code

Type of Change

• Bugfix (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

• This is a non-implementation change (Documentation, Tooling, or CI only)
• No interpretation — Keys treated as opaque strings, no structural inference
• No silent behavior — No merging, overwriting, or implicit resolution
• Boundary respected — No validation, coercion, or business logic

📘 AGENTS.md

Security & API Stability

• No security impact (forbidden keys, prototype safety unaffected)
• No changes to public API (parse, ParseResult, ParseIssue, IssueCode)
• No breaking changes; or justified with version bump rationale
• Compatible with current v0.x versioning policy

Testing

• bun run check:type:source passes
• bun run test passes
• bun run build passes

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🤖 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 (067f7da) to head (8f9bc21).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #68   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            3         1    -2     
  Lines           23        21    -2     
  Branches         5         5           
=========================================
- Hits            23        21    -2     

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