[0.64.1] Animate budget disclosure chevron

[Finesssee]

Adds a short rotation transition to the budget disclosure chevron and disables it when reduced motion is preferred.

Validation:

• git diff --check passed.
• pnpm install --frozen-lockfile --offline and the frontend production bundle passed.
• The fresh Tauri debug build was stopped when free space crossed the 30 GiB guardrail (29.91 GiB). Native Windows CUA proof is pending; no stale binary or screenshot was used.
• Independent Luna source review found no issues.