build: re-introduce lint step to ci workflow

[ffmcgee725]

Explanation

Initially this job was deactivated, as a lot of files where not passing lint checks due to previously using biome in metamask-sdk, and now we switching to prettier to keep with organization conventions, as well as a lot of stuff being outside the configured conventions of monorepo (one example is using interface instead of type).

This PR here will re-introduce the job that runs yarn lint.

https://consensyssoftware.atlassian.net/browse/WAPI-796

Approach

The strategy prioritizes stability over refactoring:

• Use eslint-disable comments for intentional patterns and external constraints
• Make minimal safe code changes (formatting, explicit return types)
• Avoid behavior-changing modifications

---

Error Categories & Solutions

1. Naming Convention Violations (@typescript-eslint/naming-convention)

Pattern	Example	Solution
Snake_case RPC methods	eth_sendTransaction, wallet_getCapabilities	File-level disable - RPC spec uses snake_case
Snake_case API schemas	mmconnect_version, dapp_id	File-level disable - Auto-generated analytics schema
Short type parameters	T, K	File-level disable - Standard TypeScript conventions
External library names	AsyncStorage, Bowser	Line-level disable - External API naming
Test mock prefixes	__mockFetch, __storage	File-level disable - Common testing pattern

2. Restricted Globals (no-restricted-globals)

Global	Context	Solution
window, document	Browser-specific code, polyfills	File-level disable - Intentional browser APIs
Buffer	Polyfill shims	File-level disable - Required for cross-platform
process	Node.js playground, build configs	File-level disable - Node.js environment
alert	Browser playground feedback	File-level disable - Demo code

3. Import/Export Rules

Rule	Context	Solution
import-x/no-unassigned-import	Polyfills, mock setup	File-level disable - Side-effect imports are intentional
import-x/order	Test files with mock dependencies	File-level disable - Import order affects mock behavior
import-x/no-nodejs-modules	Buffer polyfill	File-level disable - Required for RN/browser

4. Function/Method Rules

Rule	Context	Solution
@typescript-eslint/explicit-function-return-type	Config files, test helpers, demo code	File-level disable or added explicit void returns
no-empty-function	Modal stubs, mock implementations	Added // No-op comments with void return types
@typescript-eslint/no-misused-promises	Event handlers	File-level disable - Async handlers are intentional

5. Class Property Syntax (no-restricted-syntax)

Pattern	Solution
Private class fields without #	File-level disable or migrated to #property syntax where safe
Parameter properties	File-level disable - Constructor shorthand is intentional

6. Test-Specific Rules

Rule	Context	Solution
@typescript-eslint/no-shadow	Vitest globals (describe, it, expect)	File-level disable
id-length	Vitest alias t	File-level disable - Standard pattern
@typescript-eslint/unbound-method	Mock assertions	File-level disable
promise/param-names	Test promise patterns	File-level disable

7. JSDoc Rules

Rule	Solution
jsdoc/require-param-description	File-level disable for complex nested params and test helpers
jsdoc/require-returns	File-level disable for auto-generated or obvious returns

8. Other Patterns

Rule	Context	Solution
id-denylist (err)	Catch clauses	File-level disable or renamed to error
@typescript-eslint/prefer-nullish-coalescing	Empty object fallbacks in configs	Changed || to ?? or file-level disable
no-async-promise-executor	Complex async flows	File-level disable - Async executor needed
require-unicode-regexp	Webpack/test configs	File-level disable

---

TypeScript Configuration Changes

• packages/connect-multichain/tsconfig.json: Removed test file exclusions to enable type-aware linting
• packages/connect-evm/tsconfig.json: Removed test file exclusions
• playground/playground-ui/tsconfig.json: Removed test file exclusions
• playground/node-playground/tsconfig.json: Enabled strict: true for nullish coalescing rules
• integrations/wagmi/tsconfig.node.json: Added strictNullChecks: true

---

Auto-Generated Files

Files marked with /* eslint-disable -- AUTO-GENERATED FILE */:

• playground/*/src/wagmi/metamask-connector.ts (copied from integrations/wagmi/)
• packages/analytics/src/schema.ts (API schema types)

---

Code Changes (Non-Disable)

Minimal code changes were made where safe:

• Added explicit void return types to empty methods
• Changed || to ?? for nullish coalescing where behavior is identical
• Fixed type vs interface for Wagmi module augmentation
• Fixed import ordering in test files where order affects mock behavior

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed, highlighting breaking changes as necessary
• I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes