Non-Equilibrium Holographic Brane Cosmology in AdS5. I-B: 5D Stellar Collapse, Modified Shiromizu-Maeda-Sasaki Bounce Dynamics, and Primordial CMB Signatures

While the algebraic reduction of the de Sitter static patch to a hyperfinite Type II_1 von Neumann factor resolves the horizon information paradox (as demonstrated in Paper I-A of this series), a complete quantum cosmological framework must also eliminate the initial Big Bang curvature singularity and explain the microscopic origin of the positive four-dimensional cosmological constant Lambda_4^eff > 0. In this second work (Paper I-B), we formulate the non-equilibrium five-dimensional bulk dynamics governing our observable universe as a metastable Karch-Randall 3-brane nucleated by the gravitational collapse of a hypermassive stellar progenitor in an asymptotically Anti-de Sitter spacetime (AdS5). Starting from the five-dimensional Einstein-Hilbert-Gibbons-Hawking-York action and applying the Israel-Lanczos junction conditions across a Z_2-symmetric moving hypersurface, we perform a rigorous Gauss-Codazzi geometric projection to derive the complete Modified Shiromizu-Maeda-Sasaki (SMS) field equations on the brane. We demonstrate that the interplay between the projected five-dimensional electric Weyl tensor E_munu^(5) (which induces a braking Weyl dark radiation fluid -mu_5/a^4), the quadratic Israel extrinsic curvature tensor Pi_munu(T^mat), and high-density quantum loop-brane repulsion (rho_crit ~ M_5^4) enforces a strictly positive cosmic acceleration (a''_min > 0) at the kinematic turning point H = 0. This mechanism replaces the classical a -> 0 Big Bang singularity with a regular, unitary quantum bounce. Finally, we propagate gauge-invariant Mukhanov-Sasaki curvature and tensor perturbations across the bounce barrier, deriving three falsifiable observational signatures in the Cosmic Microwave Background (CMB): an exponential infrared power suppression at ell = 2, 3 fixing k_bounce ~ (2.1 +/- 0.4) * 10^-4 Mpc^-1, a resonant non-local flattened bispectrum with f_NL^resonant ~ 2.5–5.0, and a Kaluza-Klein logarithmic modification to the inflationary tensor consistency relation bounding the bulk curvature radius to L_5 <= 1.8 * 10^-28 m.