test(regression): remove redundant folders.spec.ts (covered by sibling specs)

[daniellicnerski1]

Summary

`folders.spec.ts` had 3 tests that are already covered by sibling specs in `tests/tests-automations/regression/core-functionality/project-management/`. Removing it to reduce duplication and the maintenance surface, with no loss of behavioral coverage.

Overlap analysis

folders.spec.ts test	Existing coverage
1. CRUD folders (create / rename / delete via UI, toast assertion)	`folder-deletion-integrity.spec.ts` covers create + rename + delete via UI more thoroughly (4 deletion scenarios vs. 1 happy path)
2. add a flow into a folder by drag and drop	`folder-drag-drop-flow.spec.ts` covers the placement / move-between-folders behavior (3 tests at API + UI listing)
3. change flow folder	`general-bugs-move-flow-from-folder.spec.ts` does the exact same behavior with a direct `dragTo` instead of the `moveFlowToProject` POM method

Why this is safe

• `grep -rn "folders.spec" .github/ scripts/ tests/` → zero references. Nothing imports or references this file by name (CI workflows, helper scripts, other specs).
• `npm run typecheck` → clean after deletion. No type-level dependency on the file.
• QA-CHECKLIST.md §10.1 bullets describe behaviors (not files); they remain `[-]` because the underlying behaviors are still covered by the sibling specs (which are not yet `@stable`). The auto-generated Coverage Summary table and Phase 0 block will adjust on the next merge to `main` via `update-coverage-summary.yml`.

Test plan

• `npm run typecheck` — clean after deletion
• No external references to `folders.spec` (grep over `.github/`, `scripts/`, `tests/`)
• Behavior coverage preserved via the 3 sibling specs listed above