[PWGJE] jetChargedV2 task: unify in-/out-of-plane selection for jet pT and background fluctuations

[YubiaoWang]

1. Jet pT and background fluctuations now use the same event-plane definition: Δφ = φ − Ψ₂(FT0C, corrected Q-vector) in [0, 2π), with the same three-window in-/out-of-plane selection.
2. The folded 0–π version moved for QC.
3. Fixed Fluctuation histograms centrality region, and direct h2 in-/out-of-plane histograms are now provided for both the median_rho and the local_rho variants.

[github-actions]

O2 linter results: ❌ 0 errors, ⚠️ 0 warnings, 🔕 0 disabled