Replace manual environment variable parsing with envy for structured configuration. Updates dotenv to dotenvy (maintained fork), adds dedicated Config struct with Railway-specific settings, and consolidates all environment variable access. Upgrades reqwest to 0.12.
Configure release profile with aggressive size optimizations:
- Set opt-level to 'z' for minimum binary size
- Enable LTO for better optimization across crates
- Strip debug info to reduce final binary size
- Use panic=abort to eliminate unwinding machinery
- Reduce codegen units to 1 for maximum optimization
- Keep overflow checks for safety in production
