[defer] fix(tests): clear #9737 release gate blockers

[diegosouzapw]

Closes #9737

Base-red repair limited to test infrastructure and regressions:

• remove 7 ESLint errors (explicit test types / no any);
• replace synthetic response and request-body branching with platform Response / Request behavior so test-masking checks exercise the real primitives;
• resolve committed conflict markers and remove an incomplete duplicate test fragment.

Validation:

• npm run typecheck:core
• node scripts/check/check-test-masking.mjs
• npx eslint --suppressions-location config/quality/eslint-suppressions.json --no-ignore on all changed tests
• node --import tsx/esm --test on all changed test files: 65 passed, 0 failed
• git diff --check
• partial npm run check:release-green: typecheck, global ESLint (0 errors/0 warnings), DB rules, public creds, and complexity ratchets passed. The prior full run surfaced the additional Poe test-masking violation fixed in this PR; the old run was then superseded.

[diegosouzapw]

⚠️ This PR branch is currently held by an active worktree session (Rule #22b). Keep as deferred until ownership is released.

⚠️ Review held: this PR branch is owned by an active parallel worktree session. Keep it in defer until ownership is released and re-run this PR assessment.

[diegosouzapw]

⚠️ This PR branch is currently held by an active worktree session (Rule #22b). Keep as deferred until ownership is released.

⚠️ Review held: this PR branch is owned by an active parallel worktree session. Keep it in defer until ownership is released and re-run this PR assessment.

[diegosouzapw]

⚠️ This PR branch is currently held by an active worktree session (Rule #22b). Keep as deferred until ownership is released.

⚠️ Review held: this PR branch is owned by an active parallel worktree session. Keep it in defer until ownership is released and re-run this PR assessment.