This arXiv white paper (preprint, not peer-reviewed) advocates sustained Hubble UV observations of young solar-like stars to probe magnetic activity, superflares, and energetic particles that sculpt early planetary atmospheres. Unlike targeted studies of individual systems such as EK Draconis, the proposal frames clusters of young analogs as natural laboratories exposing statistical patterns in space-weather forcing missed by mature-star data. Drawing on multi-wavelength context from TESS flare statistics and Chandra open-cluster surveys, the analysis shows how FUV/NUV diagnostics calibrate atmospheric escape models that JWST transmission spectra alone cannot constrain. Limitations include reliance on extrapolated solar scaling laws and small existing UV samples of solar analogs younger than 500 Myr. A related peer-reviewed study (Airapetian et al., ApJ 2021) quantified CME impacts on early Earth analogs, while a TESS-based analysis (Feinstein et al., AJ 2022) catalogued flare frequencies across 10^4 young stars yet lacked UV line diagnostics essential for particle-acceleration physics. Together these threads indicate that coordinated HST campaigns could reduce uncertainties in long-term ozone and water-loss predictions by factors of two to three, directly informing target selection for the Habitable Worlds Observatory.