Fix TanStack Router lint resolution in test app

[watson]

Motivation

The TanStack Router test app was already importing @datadog/browser-rum-react/tanstack-router, but our TypeScript config did not include a matching path alias for that subpath. As a result, type-aware ESLint could not resolve the import and yarn lint failed.

Changes

• add the missing @datadog/browser-rum-react/tanstack-router path alias to the repo-level tsconfig.base.json
• add the same path mapping to test/apps/tanstack-router-app/tsconfig.json so the test app's local type-aware linting also resolves the package correctly

This is a config-only fix. It does not change runtime behavior.

Test instructions

1. Check out this branch.
2. Run yarn lint from the repository root.
3. Confirm the previous lint error in test/apps/tanstack-router-app/app.tsx no longer appears.

Checklist

• Tested locally
• Tested on staging
• Added unit tests for this change.
• Added e2e/integration tests for this change.
• Updated documentation and/or relevant AGENTS.md file

[watson]

• Add Live Debugger package #4449 : 6 dependent PRs (#4480 , #4503 , #4508 and 3 others)
• Fix TanStack Router lint resolution in test app #4513 👈 (View in Graphite)
• main

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[cit-pr-commenter-54b7da]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	179.16 KiB	179.16 KiB	0 B	0.00%	✅
Rum Profiler	6.16 KiB	6.16 KiB	0 B	0.00%	✅
Rum Recorder	27.03 KiB	27.03 KiB	0 B	0.00%	✅
Logs	56.65 KiB	56.65 KiB	0 B	0.00%	✅
Rum Slim	135.00 KiB	135.00 KiB	0 B	0.00%	✅
Worker	23.63 KiB	23.63 KiB	0 B	0.00%	✅

🚀 CPU Performance

Action Name	Base CPU Time (ms)	Local CPU Time (ms)	𝚫%
RUM - add global context	0.004	0.007	+75.00%
RUM - add action	0.0133	0.0228	+71.43%
RUM - add error	0.0129	0.0262	+103.10%
RUM - add timing	0.0028	0.0051	+82.14%
RUM - start view	0.0127	0.0208	+63.78%
RUM - start/stop session replay recording	0.0007	0.0012	+71.43%
Logs - log message	0.0202	0.0264	+30.69%

🧠 Memory Performance

Action Name	Base Memory Consumption	Local Memory Consumption	𝚫
RUM - add global context	32.43 KiB	30.63 KiB	-1.80 KiB
RUM - add action	105.60 KiB	92.94 KiB	-12.66 KiB
RUM - add timing	31.89 KiB	32.77 KiB	+901 B
RUM - add error	99.80 KiB	95.19 KiB	-4.60 KiB
RUM - start/stop session replay recording	31.26 KiB	32.26 KiB	+1022 B
RUM - start view	507.19 KiB	486.70 KiB	-20.49 KiB
Logs - log message	100.24 KiB	105.37 KiB	+5.13 KiB

🔗 RealWorld

[datadog-prod-us1-6]

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 77.03% (-0.01%)

_{This comment will be updated automatically if new data arrives.
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