Replace the 328-line Start() god function with a Server struct +
11 named handler methods. Routes registered in routes(), middleware
applied in one place.
Start() kept as a convenience wrapper (NewServer + Start) so
existing callers don't need to change unless they want the Server
reference.
Each handler is now independently readable and testable without
parsing a 300-line closure nest.
New cmd/uptop/config.go with appConfig struct + parseConfig() that
reads all 25 UPTOP_* env vars in one place with defaults. Replaces
~120 lines of scattered os.Getenv calls in runServe.
runServe now reads cfg := parseConfig() up front. ServerConfig
built via cfg.serverConfig(). Uniform flag > env > default
precedence for port/db-type/dsn via flag defaults from config.
lerko
