Dynamic Vacuum Theory (DVT) v26 — Part IV: Zero-Parameter Resolution of the X-Ray Galaxy Cluster Mass Discrepancy (Coma, Perseus, Virgo) and the Bullet Cluster Cavitation Offset via 3D Spherical Vacuum Flux Projection

Since Fritz Zwicky's 1933 virial analysis of the Coma Cluster (Abell 1656), rich galaxy clusters have served as the primary observational pillar for cold dark matter (LCDM). While classical Modified Newtonian Dynamics (MOND, a_0 = 1.2 x 10^-10 m/s^2) successfully describes spiral galaxy rotation curves, it systematically underpredicts the X-ray hydrostatic dynamical mass of rich galaxy clusters by a factor of 1.6 to 2.2, forcing MOND models to reintroduce 2 eV sterile neutrinos or residual dark matter cores. In this fourth installment of the Dynamic Vacuum Theory (DVT v26) series, we prove that the "cluster missing mass problem" is an artifact of applying a 2D planar disk acceleration threshold to a 3D spherically compressed intracluster plasma reservoir. In Part I (DOI: 10.5281/zenodo.23741503), we established that planar flux leakage across a thin 2D spiral disk (h_z/R << 1) reduces the 3D vacuum permeability by the exact geometric projection integral C_proj = 2/pi = 0.63662, yielding a_0,disk = c*H_0 / 4 = 1.700232 x 10^-10 m/s^2. In rich, virialized 3D X-ray galaxy clusters (h_z/R -> 1), spherical flux confinement restores the exact inverse geometric factor C_proj^-1 = pi/2 = 1.57080, elevating the 3D cluster vacuum phase transition threshold to: a_0,cluster = (pi / 2) * a_0,disk = (pi * c * H_0) / 8 = 2.670718 x 10^-10 m/s^2 with ZERO free parameters (0-fit). Coupling this exact threshold to the Cavaliere–Fusco-Femiano beta-model of X-ray surface brightness and DVT–Navier–Stokes hydrostatic equilibrium reproduces the observed Chandra, XMM-Newton, Hitomi/XRISM, and SRG/eROSITA dynamical profiles across key benchmark clusters without dark matter: Coma Cluster (Abell 1656, R_500 = 1000 kpc, k_B*T_X = 8.25 keV, r_c = 290 kpc, beta = 0.75): Baryonic mass M_b = 1.25 x 10^14 M_sun yields DVT dynamical mass M_dyn,DVT = 5.00 x 10^14 M_sun vs. observed 5.10 x 10^14 M_sun (1.96% error). Perseus Cluster (Abell 426, R_500 = 1000 kpc, k_B*T_X = 6.40 keV, r_c = 115 kpc, beta = 0.65): Baryonic mass M_b = 1.05 x 10^14 M_sun yields M_dyn,DVT = 4.57 x 10^14 M_sun vs. observed 4.60 x 10^14 M_sun (0.72% error), while reproducing the Hitomi/XRISM inner-core turbulent velocity dispersion (sigma_v,DVT = 162.8 km/s vs. observed 164 +/- 10 km/s, 0.73% error). Virgo Cluster (M87 Core at 100 kpc & Spiral-Rich Outer Halo at 300 kpc): Demonstrates the 3D-to-2D geometric transition within a single cluster, predicting 9.09 x 10^12 M_sun in the 3D M87 core (vs. observed 9.14 x 10^12 M_sun, 0.55% error) and 4.16 x 10^13 M_sun in the outer halo (vs. observed 4.20 x 10^13 M_sun, 0.86% error). Bullet Cluster (1E 0657-558) & Abell 520: Hyperbolic superfluid vacuum wave relaxation (tau_relax = pi * R_core / c_s) reproduces the 219.8 kpc weak-lensing-to-X-ray cavitation offset (vs. observed 220.0 +/- 15 kpc, 0.10% error) and explains the central acoustic standing-wave dark core of Abell 520. Companion Series DOIs: 10.5281/zenodo.23741503 (Part I), 10.5281/zenodo.23741719 (Part II), 10.5281/zenodo.23894218 (Part III / Falsifiable Predictions) | Amazon Monograph ASIN: B0HQ2DBZDR