v3.25.2
Redeemable Convertible Preferred Stock and Stockholders' Deficit - Redeemable Shares (FY) (Details) - USD ($)
$ / shares in Units, $ in Thousands
 1 Months Ended 3 Months Ended 6 Months Ended 12 Months Ended
May 31, 2024
Jan. 31, 2024
May 31, 2023
Apr. 30, 2023
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Dec. 31, 2024
Dec. 31, 2023
Class of Stock [Line Items]                    
Shares authorized (in shares)                 206,169,000 176,646,000
Options granted to purchase redeemable convertible peferred stock (in shares)             0 0 0 23,300,000
Stock issuance cost             $ 27,763 $ 0    
Dividends paid-in-kind           $ 15,582        
Class A common stock issued upon conversion of redeemable convertible preferred stock (in shares)                 1 1
Common stock price to trigger mandatory conversion of redeemable preferred stock                 $ 6.97  
Minimum net IPO proceeds to trigger mandatory conversion of redeemable preferred stock                 $ 125,000  
Series B Redeemable Convertible Preferred Stock                    
Class of Stock [Line Items]                    
Shares authorized (in shares)       79,978,760            
Temporary equity par value (in dollars per share)       $ 0.000005            
Issuance of redeemable convertible preferred stock (in shares)                   75,495,640
Proceeds from issuance of redeemable convertible preferred stock                   $ 421,000
Redeemable convertible preferred stock issued upon exercise of tranche liability (in shares)   4,483,120 35,864,920              
Fair value adjustment loss                 $ (105,000) $ 0
Consent threshold, redeemable convertible preferred stock                 20.00%  
Series B Redeemable Convertible Preferred Stock | Lead Investor                    
Class of Stock [Line Items]                    
Issuance price per share (in dollars per share)       5.58           $ 5.58
Options granted to purchase redeemable convertible peferred stock (in shares)                   40,348,040
Options grant period                 9 months  
Series B-1 Redeemable Convertible Preferred Stock                    
Class of Stock [Line Items]                    
Temporary equity par value (in dollars per share)       $ 0.000005            
Issuance of redeemable convertible preferred stock (in shares)       12,484,540            
Series B-1 Redeemable Convertible Preferred Stock | Lead Investor                    
Class of Stock [Line Items]                    
Issuance price per share (in dollars per share)       $ 0.4            
Series C Redeemable Convertible Preferred Stock                    
Class of Stock [Line Items]                    
Temporary equity par value (in dollars per share) $ 0.000005                  
Issuance of redeemable convertible preferred stock (in shares) 29,523,120                  
Proceeds from issuance of redeemable convertible preferred stock $ 1,100,000                  
Stock issuance cost $ 3,000                  
Class A common stock issued upon conversion of redeemable convertible preferred stock (in shares)                 1.0119  
Series C Redeemable Convertible Preferred Stock | Lead Investor                    
Class of Stock [Line Items]                    
Issuance price per share (in dollars per share) $ 38.95                  
Series C                    
Class of Stock [Line Items]                    
Shares authorized (in shares)                 29,523,000  
Issuance price per share (in dollars per share)                 $ 38.95  
Dividend rate                 10.00%  
Cash dividends paid                 $ 59,000  
Dividends paid-in-kind                 16,000  
Change in accumulated stated value of redeemable preferred stock                 $ 14,000  
Consent threshold, redeemable convertible preferred stock                   90.00%
Redemption price of common stock issued upon conversion of convertible preferred stock (in dollars per share)                 $ 38.95  
Redeemable Class A Common Stock                    
Class of Stock [Line Items]                    
Temporary equity par value (in dollars per share)         $ 0.000005   $ 0.000005   $ 0.000005  
Cash dividends paid         $ 0 $ 0 $ 29,000 $ 0    
Redeemable Convertible Preferred Stock                    
Class of Stock [Line Items]                    
Shares authorized (in shares)         0   0   206,169,000 176,646,000
Temporary equity par value (in dollars per share)         $ 0.000005   $ 0.000005   $ 0.000005 $ 0.000005
Issuance of redeemable convertible preferred stock (in shares)                 4,483,000 75,496,000
Redemption grace period after transaction, redeemable preferred stock                 90 days