ESFEX v0.1.2

Added

• Benders decomposition as an optional master-problem solver
  (master_problem.solver_method: monolithic | benders). An investment-only
  master with θ[y] recourse variables plus per-representative-day dispatch
  subproblems and optimality cuts — beneficial for very large problems.
  Configurable (benders_max_iterations, benders_tolerance,
  benders_lol_penalty_cap) and selectable from the Studio's master-problem
  settings. Monolithic remains the default.
• OpenSSF Best Practices badge.

Fixed

• Grid Builder bus-distribution step no longer freezes the UI on
  whole-country footprint sets: classification and nearest-bus assignment run
  in a background thread, with a vectorised classifier, a single centroid pass,
  and np.bincount accumulation.

Full changelog: v0.1.1...v0.1.2