docs(README): add section on BigInt support for large numeric IDs

[wesleyschlenker]

Simply adds documentation to clarify how to work with json-bigint implementation.

Summary by CodeRabbit

• Documentation
  • Added guidance on handling very large numeric IDs that can exceed safe integer limits, explains representation as big-number objects, and shows patterns and examples for converting IDs to string form for safe display and serialization.
• Chores
  • Bumped package version to 4.0.1.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between b8bf38a and 828ee60.

📒 Files selected for processing (1)

• package.json

✅ Files skipped from review due to trivial changes (1)

• package.json

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📝 Walkthrough

Walkthrough

Added documentation explaining that Strava numeric IDs may exceed Number.MAX_SAFE_INTEGER, showing how to parse with json-bigint and convert BigNumber IDs to strings for display/serialization; also bumped package version from 4.0.0 to 4.0.1. No functional code changes.

Changes

Cohort / File(s)	Summary
Documentation – BigInt Support README.md	Added "Large numeric IDs (BigInt support)" section describing overflow risk, recommending json-bigint for parsing, and showing example conversion of BigNumber activity IDs to strings. Documentation-only.
Metadata – Version Bump package.json	Incremented package version from 4.0.0 to 4.0.1. No code or API changes.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

🐰
I twitch my whiskers at digits so tall,
When numbers outrun Number.MAX_SAFE_INTEGER's call,
I parse them with care and convert them to string,
No more lost IDs — I make the big numbers sing.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: adding documentation about BigInt support for large numeric IDs to the README, which aligns with both the file changes and PR objectives.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch 168-docs-need-updated-to-clarify-bigint-behavior

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@README.md`:
- Around line 213-214: Update the README paragraph about json-bigint to correct
the behavior: note that this codebase calls JSONbig.parse() with default
options, so large numeric values are returned as bignumber.js BigNumber objects
(not native JS BigInt), and mention that native BigInt would only be returned if
JSONbig is configured with useNativeBigInt: true; reference JSONbig.parse() and
the useNativeBigInt option in the explanation so readers know how to enable
native BigInt if desired.

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ℹ️ Review info

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between a399263 and 6224b7f.

📒 Files selected for processing (1)

• README.md

[markstos]

Seems excellent.