Identifying the near-horizon black hole microstates which produce the correct black hole entropy formula is a fundamental open problem in theoretical physics, and at the same time, it is the ultimate aim of AdS/CFT holography. Quiver quantum mechanics captures the bound states of D-brane constituents of 4-dimensional extremal black holes. It is a unique description compared to all previously known examples of CFTs in the context of AdS/CFT correspondence because it allows a direct interpretation of its ground states as bound states of BPS (Bogomolny-Prasad-Sommerfield) black holes in four-dimensional supergravity. Conformal symmetry appears in the scaling limit of the effective Coulomb branch quiver mechanics. We recently developed a geometric gauged sigma model reformulation for this model as a type-B superconformal mechanics. It is a powerful interpretation because it provides a differential geometric description for the Hilbert space. Using this formulation as our groundwork, we will obtain a definitive result for the ground state degeneracies of the scaling quiver quantum mechanics by applying regularisation and Atiyah-Bott localisation techniques that were applied before for type-A superconformal mechanical models. Furthermore, this computation will provide the first-ever superconformal index computation for type-B models. Through the microscopic entropy computation, we will obtain an identification of the ground states of quiver D-brane quantum mechanics with pure AdS(2) black hole microstates, and hence the first ever evidence for the pure AdS(2)/CFT(1) holography. We will use this result to resolve long-standing problems about the AdS(2) BPS black holes in the supergravity regime. For example, we will determine the existence of a possible (topological) quantum hair for AdS(2) scaling black holes, thereby obtaining concrete evidence either for the traditional empty-space or the fuzzball picture for the horizon neighbourhood of this class of black holes.