Say when a newer release is out, and stop there

A check on the releases page once a day: at start, on a timer while Dikte
runs, from the General tab on demand, and from `dikte update` at a terminal.
What it finds goes in the tray menu and in one notification per version, and
opens the release page.

Nothing is downloaded and nothing is installed. The four downloads are
installed four different ways and three of those belong to the platform: a
Mac bundle cannot rewrite itself while it is running, the Windows setup has
an uninstall entry of its own, an AppImage is a file kept wherever its owner
keeps it, and a checkout is updated with git. Being wrong about any one of
them means an installation somebody has to repair by hand.

Versions are compared by their numbers alone. A build off master carries the
released number with its commit after it, and that build is ahead of the
release it names rather than behind it; read as a version suffix, every
nightly would be told to go back to a release it had already passed.

The clock lives in its own file rather than in the settings, since a check
runs while the settings window may be open and a background write into
config.json is what would overwrite whatever it holds.

README.md

@@ -107,7 +107,10 @@ Meetings are not supported there yet; the details are in the
 two global shortcuts, whose keys are its two arguments, or the ones already in
 your settings when it is given none. `./scripts/update.sh` pulls and puts all of
 that back; `./scripts/uninstall.sh` takes it away again and leaves your settings
-and dictations alone unless you pass `--purge`.
+and dictations alone unless you pass `--purge`. Dikte looks at the releases page
+once a day and puts a line in the tray menu when a newer version is out, which
+opens the page rather than installing anything; the General tab turns that off
+or runs it on the spot.
 
 Speech to text and cleanup each pick a provider in the settings window, and both
 run here by default, on models of your own. The cloud is the other option:
@@ -130,6 +133,7 @@ set next to it.
 | Speak a command to an agent | Tray menu → *Ask Claude*, or `dikte ask` |
 | Start / end a meeting | Tray menu → *Record a meeting*, or `dikte meeting` |
 | Settings | Tray menu → *Settings*, or `dikte settings` |
+| Look for a newer version | General tab → *Check now*, or `dikte update` |
 | Reload after an update | Tray menu → *Restart*, or `dikte restart` |
 | Quit | Tray menu → *Quit*, or `dikte quit` |
 
@@ -240,6 +244,7 @@ api.py            transcription and cleanup requests (stdlib only)
 cleanup.py        who rewrites the transcript: OpenRouter, here, Claude or Codex
 ggml.py           whisper.cpp and llama.cpp here: fetch, verify, keep serving
 hub.py            what GitHub and Hugging Face have on offer today
+update.py         whether a newer release is out, and the page it is on
 worker.py         transcribe → clean up → clipboard → paste
 vad.py            deciding whether a recording holds speech at all
 filetranscribe.py file transcription: ffmpeg, chunking, timestamps