v1.1.2 — code-audit fixes

Bug fixes from a full code audit (all backward-compatible):

• --once no longer hangs when the cooler isn't found — it makes one attempt and exits.
• A transient sensor read error no longer crashes the daemon (e.g. hwmon renumbering on suspend/resume) — the frame is skipped and it continues.
• self-update reports failure instead of falsely claiming success if the service restart fails.
• install.sh: AW5D_BIN_DIR to a system dir now sudo-writes the launcher; a missing systemd --user session fails early with a clear message; --uninstall cleans up config + the bootstrap checkout; sed metachars in the Python path are escaped.
• just set-interval edits only the interval line instead of overwriting the whole config file.
• Clean shutdown (no traceback on an ill-timed SIGTERM), plus regression tests for --once.