chore: modernize tooling, remove dead code, and rewrite docs

[alainncls]

Summary

Modernize the project tooling, remove dead code, and overhaul documentation.

• Tooling: Replace Babel with ts-jest for testing; migrate ESLint from legacy
  config (v8) to flat config (v9) with typescript-eslint; simplify Husky hook;
  bump GitHub Actions (checkout, setup-node, setup-python) to v6.
• Cleanup: Remove axios and the unused CoinGecko / CoinMarketCap logo-fetching
  module (src/utils/logo.ts), the checkTokenExists helper, and all related config
  entries (COINMARKETCAP_API_KEY, COINGECKO_URL, COINMARKETCAP_URL). Drop 7
  unnecessary dev-dependencies.
• Type safety: Change readJsonFile return type from any to unknown, type
  saveJsonFile input as LineaTokenList, and call validateConfig() at startup.
• Docs: Rewrite README.md (project structure, commands table, CI/CD overview),
  rewrite docs/development.md (environment variables reference, structured field
  table), add CONTRIBUTING.md, and improve the PR template with a type-of-change
  section and additional checklist items.
• Scripts: Rename prettify → prettier for consistency; remove the deprecated
  precommit script.

---

Note

Medium Risk
Mostly build/test/lint/documentation changes, but upgrading ESLint/Jest tooling and enforcing runtime config validation can cause CI or developer workflow breakages if any assumptions or configs are off.

Overview
Modernizes the repo’s tooling and CI: migrates ESLint to v9 flat config (eslint.config.js) with typescript-eslint, replaces Babel-based Jest transforms with ts-jest, simplifies Husky pre-commit to run lint + prettier, renames formatting scripts from prettify→prettier, adds a typecheck script, and bumps GitHub Actions (checkout, setup-node, setup-python) to v6.

Cleans up unused configuration and dependencies by removing CoinMarketCap/CoinGecko-related env/config fields (and COINMARKETCAP_API_KEY from .env.example), dropping axios and other no-longer-needed dev deps, and tightening type-safety by changing JSON file helpers to unknown/LineaTokenList and validating config on startup; documentation and contribution workflow are refreshed via a rewritten README, updated docs/development.md, new CONTRIBUTING.md, and an expanded PR template/checklist.

^{Written by Cursor Bugbot for commit 2f47a12. This will update automatically on new commits. Configure here.}

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	npm/​typescript-eslint@​8.56.0
	npm/​eslint@​8.57.1 ⏵ 9.39.2	-7		+1	+45
	github/​actions/​setup-python@​a26af69be951a213d495a4c3e4e4022e16d87065 ⏵ e797f83bcb11b83ae66e0230d6156d7c80228e7c	+1
	github/​actions/​checkout@​93cb6efe18208431cddfb8368fd83d5badbf9bfd ⏵ de0fac2e4500dabe0009e67214ff5f5447ce83dd	+1

View full report

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

[eloi010]

LGTM