Show running games in Discord as Rich Presence

Watch /proc for Steam games (by app ID, from Steam's reaper process) and
other games (by executable, from Discord's detectable list), and report
the first one to Discord's IPC socket with the game's own app ID.

config.example.toml

@@ -0,0 +1,14 @@
+# ~/.config/discord-game-presence/config.toml (all keys optional)
+
+# Seconds between process scans.
+interval = 5
+
+# Also match Discord's Linux executable names (off: they can match ordinary tools).
+linux_executables = false
+
+# Never show these games: Discord app IDs or names.
+ignore = ["Some Game"]
+
+# Extra executables: name or path suffix (case-insensitive) -> Discord app ID.
+[executables]
+"mygame.exe" = "123456789012345678"