This change tweaks the startup message in src/server.c so running without --writable now logs a warning instead of a notice, and it also adds a newline for cleaner output. The behavior itself is unchanged, but the message is now more visible in logs when the server starts in readonly mode. Practical effect: it's easier to notice configuration mistakes before wondering why writes are disabled.

Updated the server startup log to emit the readonly-mode notice as a warning so the missing `--writable` flag is easier to spot. - zhengqunkoo/ttyd