[blue219]

Brief summary

Migrate foundation utilities, request helpers, and Logger to strict TypeScript while preserving their CommonJS exports and runtime behavior.

Depends on #5664. Merge order: #5664, this PR, then #5666. Until #5664 merges, GitHub's master-based diff includes its preparation commits. Review only this batch.

Which issue is fixed?

No linked issue. This is the first application-code batch of the incremental backend TypeScript migration.

In-depth Description

• Type constants, extension lists, equivalence comparison, series-string parsing, request helpers, and the Logger singleton.
• Preserve mutable exports, native coercion and error cases, ordinary logging return values, awaited fatal logging, and logging before manager initialization.
• Add the Express development types and a small date-formatting boundary declaration outside the embedded library directory so its JavaScript entry remains compiled. Existing locked dependency versions and runtime dependencies are unchanged.
• Add compile-only export contracts and targeted compatibility cases. The first commit only renames the six source files; every rename reports R100. The second commit adds types and tests.

How have you tested this?

Validated on Node.js 24.22.0:

npm ci --no-audit --no-fund
npm run typecheck:server
npm run lint
npm run clean:server
npm run build:server
npx --no-install mocha dist-server/test/server/Logger.test.js dist-server/test/server/utils/foundationUtils.test.js dist-server/test/server/utils/requestUtils.test.js

All 42 targeted tests passed. Native string coercion is preserved without weakening strict ESLint.

Verified the pure-rename commit with git diff-tree --no-commit-id --name-status -r -M 37dec873 and checked that documentation and unrelated migrations are excluded. No additional functional manual testing is required for this batch; full unit and packaging/startup checks run in the existing fork CI.

CI passed on the same commit in the fork:

• Unit tests: lint, type checking, and all 380 tests passed.
• Integration test: client build, server compilation, binary packaging, startup, and HTTP availability passed.

Upstream workflows currently require maintainer approval before running.

Screenshots

Not applicable; no web client changes.

[nichwall]

This looks good to me. Thanks!