Fix Typescript errors and clean up TS configs

[fredrikekelund]

Related issues

Fixes STU-1373

Proposed Changes

We currently have a few TS errors in our code. This PR addresses that with the following changes:

• Add a typecheck npm script.
• Update AGENTS.md to tell agents to do type checking.
• Run that script as part of the lint CI job.
• Removed "*": [ "node_modules/*" ] resolvers in tsconfig.json files. This means it's no longer possible to import any code from node_modules files. Instead, we use regular module resolution to import available modules.
  • This may sound like a big change, but it's really not. I only had to apply a minor edit to a single file (use-update-button-tooltip.ts) to make this work.
• Install @types/glob and wpcom to prevent TS from complaining.
• Externalize yargs dependency during build. This is a different way of tackling the issue raised in Fix Studio CLI yargs locale strings displaying in English #2609. I had to address this because yarg's updateStrings function didn't play nice with the type definitions from apps/cli/lib/i18n.ts. By not bundling the yargs code, we sidestep the problem altogether.
• Fix all other type errors.

Testing Instructions

CI should pass.

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[wpmobilebot]

📊 Performance Test Results

Comparing 8ac4a6f vs trunk

site-editor

Metric	trunk	8ac4a6f	Diff	Change
load	1473.00 ms	1763.00 ms	+290.00 ms	🔴 19.7%

site-startup

Metric	trunk	8ac4a6f	Diff	Change
siteCreation	6058.00 ms	7075.00 ms	+1017.00 ms	🔴 16.8%
siteStartup	3959.00 ms	3944.00 ms	-15.00 ms	⚪ 0.0%

---

Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)

[sejas]

Changes look good. I tested it the app by starting a site and logging in. I also tried executing the new CLI command npm run typecheck.

[fredrikekelund]

Thanks for the review, @sejas 🙏