Rename project to GoSentry

Rename the application, Go module path, command package, build artifacts, resource script, and embedded icon assets from PySentry/pysentry to GoSentry/gosentry.

Move portable settings to gosentry.yaml while reading legacy pysentry.yaml during the transition, then rewrite settings under the new name.

Update Windows and Linux autostart integration to use GoSentry names while cleaning up legacy PySentry registry, desktop-entry, and systemd artifacts.

Refresh README, architecture notes, roadmap, changelog, and release examples for version 0.3.0.

docs/ARCHITECTURE.md

@@ -1,6 +1,6 @@
-# PySentry Architecture
+# GoSentry Architecture
 
-This document shows the current component interaction model. PySentry is still a
+This document shows the current component interaction model. GoSentry is still a
 single desktop process: the GUI, scheduler, storage, and command runner live in
 one application and communicate through Go function calls and shared in-memory
 job state.
@@ -15,7 +15,7 @@ flowchart LR
     scheduler["src/core Scheduler - @every and cron timing"]
     runner["src/core Runner - shell command execution"]
     autostart["src/core Autostart - Windows Startup shortcut / Linux desktop startup"]
-    config["pysentry.yaml - application settings"]
+    config["gosentry.yaml - application settings"]
     jobs["jobs.yaml - job definitions"]
     logs["logs_dir - per-run command output logs"]
     shell["Platform shell - cmd.exe /C or sh -c"]
@@ -41,8 +41,8 @@ flowchart LR
 ## Main Flows
 
 1. Startup:
-   The executable starts `cmd/pysentry`, which calls the GUI package. The GUI
-   opens the store, loads `pysentry.yaml` and `jobs.yaml`, creates the main tabs,
+   The executable starts `cmd/gosentry`, which calls the GUI package. The GUI
+   opens the store, loads `gosentry.yaml` and `jobs.yaml`, creates the main tabs,
    then starts the scheduler with the loaded job slice.
 
 2. Editing settings or jobs: