feat(auth): add optional HTTP Basic Auth for API and web interface

- Add --password flag and FPLCA_PASSWORD env var support
- Create LCA.Auth module with WAI middleware
- Apply middleware when password is configured
- Browsers show native login dialog, CLI uses -u :password

feat: add scientific notation formatting for inventory displays

Added Utils.Format module with formatScientific function that formats
floats to scientific notation with 2 decimal places in the mantissa.

Changes:
- Created web/src/Utils/Format.elm with formatScientific function
- Updated InventoryView.elm to format quantities (e.g., 1.23e-6)
- Updated TreeView.elm to format edge quantities consistently

Examples:
- 0.0000012302591461717608 → 1.23e-6
- 1.5047776003155534e-14 → 1.50e-14

This improves readability by replacing overly-precise decimal numbers
with clean scientific notation throughout the web UI.