Stockholder's Equity and Share-Based Compensation - Assumptions Used in Determining Fair Value & Early exercise of Stock Options (Q1) (Details) |
3 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions and Methodology [Abstract] | ||||
| Expected volatility | 93.70% | 88.40% | ||
| Risk-free interest rate | 4.10% | 4.20% | ||
| Expected term | 5 years 10 months 24 days | 6 years | ||
| Employee Stock Option | ||||
| Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions and Methodology [Abstract] | ||||
| Expected volatility | 92.40% | 93.80% | ||
| Risk-free interest rate | 3.90% | 4.10% | ||
| Expected term | 5 years 9 months 18 days | 6 years | ||