[PM-37955] Update typescript configs

[jprusik]

🎟️ Tracking

PM-37955

📔 Objective

Bumping to typescript v6 requires some project config updates to work properly

[github-actions]

🤖 Bitwarden Claude Code Review

Overall Assessment: APPROVE

This PR updates the three TypeScript project configs (scripts/, tests/, benchmarks/) in preparation for a TypeScript v6 bump. Changes include switching to node16 module/resolution, making rootDir explicit for the configs that import from sibling project directories, restricting ambient types to what each surface actually needs, and converting commented-out strict placeholders to explicit strict: false with a tracked FIXME ticket. No source code or runtime behavior changes; output layout is preserved because the new explicit rootDir: ".." matches what TypeScript was previously inferring from cross-directory imports (../constants, ../abstractions, ../fixtures).

Code Review Details

No issues identified.

Notes (informational, not findings):

• tests/tsconfig.json correctly adds "chrome" to types since tests/utils.ts uses chrome.tabs; scripts/ and benchmarks/ omit it as neither references Chrome APIs.
• rootDir: ".." is only added where needed (tests, benchmarks); scripts/ is self-contained and correctly left without it.
• The PR description says "Bumping to typescript v6", but the actual bump remains in renovate/typescript-6.x; this PR is config prep only. package.json still pins typescript: 5.9.3, which is intentional.