v3.25.2
Redeemable Convertible Preferred Stock and Stockholders' Deficit - Redeemable Common Stock, and Stockholders' Equity Deficit - Stock Option Plan (FY) (Details) - USD ($)
$ / shares in Units, $ in Millions
6 Months Ended 12 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Stock Option Plan [Abstract]          
Granted (in shares) 0 0 0 23,300,000  
Granted (in dollars per share) $ 0   $ 0 $ 3.48  
Fair value of shares vested $ 18 $ 18 $ 45 $ 10 $ 2
Intrinsic value of stock options exercised $ 170 $ 14 $ 117 $ 38 $ 0
Stock Options          
Stock Option Plan [Abstract]          
Granted (in dollars per share)       $ 6.5 $ 0.47
2019 And 2025 Plans | Stock Options | Minimum          
Stock Option Plan [Abstract]          
Vesting period 3 years        
2019 And 2025 Plans | Stock Options | Maximum          
Stock Option Plan [Abstract]          
Vesting period 4 years        
Expiration period 10 years        
2019 Plan | Stock Options          
Stock Option Plan [Abstract]          
Number of shares authorized (in shares)     73,637,600 66,637,600  
Number of shares available for grant (in shares)     3,750,480 11,061,240  
Expiration period     10 years    
2019 Plan | Stock Options | Minimum          
Stock Option Plan [Abstract]          
Vesting period     3 years    
2019 Plan | Stock Options | Maximum          
Stock Option Plan [Abstract]          
Vesting period     4 years