[Frontend] Exclude orphaned backend behavior specs from the frontend TypeScript project

## Problem

Root-level NestJS specs are included by the frontend tsconfig and reference modules that do not exist in this package.

## Relevant code

`behavior.controller.spec.ts, behavior.service.spec.ts`

## Proposed scope

Move the specs to the backend package or explicitly exclude them, then make the root type-check command pass without hiding frontend source errors.

## Acceptance criteria

- [ ] The reported behavior is reproduced or characterized with a focused automated test before the fix.
- [ ] The implementation satisfies the proposed scope without weakening TypeScript, lint, authorization, privacy, or error handling.
- [ ] Success, empty/loading where applicable, failure, and boundary cases are covered.
- [ ] Existing related tests pass and new regression coverage is included.
- [ ] User-facing behavior remains accessible by keyboard and at mobile viewport sizes where UI is affected.
- [ ] Documentation is updated when the change alters configuration, contracts, security assumptions, or contributor workflow.

## Contributor notes

Base the work on the latest `main` branch. Keep unrelated refactors out of the pull request and include screenshots or recordings for visible changes. Never use real pet, medical, contact, wallet, or credential data in fixtures.

Start by inspecting the frontend tsconfig and the root-level behavior.controller.spec.ts and behavior.service.spec.ts, then run the root type-check command to reproduce the missing-module errors. Determine whether the specs belong in the backend package or should be excluded without suppressing frontend source checks. Done means the focused regression coverage is present and the root type-check passes.

Written by the indexing model from the issue text.