Add OpenWhispr easy setup installer and companion files

Single-file bash installer (setup-openwhispr.sh) with distro detection,
dependency installation, STT/AI cleanup provider selection, API key
management, and first-run launch. Includes README, LICENSE (MIT),
CHANGELOG, .gitignore, ShellCheck CI, issue templates, PR template,
and GitHub setup guide.

https://claude.ai/code/session_01XKYC1basxdwtHy71tky7xm

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,40 @@
+---
+name: Bug report
+about: Report a problem with the installer
+title: "[Bug] "
+labels: bug
+assignees: ""
+---
+
+## Describe the bug
+
+A clear and concise description of what went wrong.
+
+## Steps to reproduce
+
+1. Run `bash setup-openwhispr.sh`
+2. Choose option ...
+3. See error ...
+
+## Expected behaviour
+
+What you expected to happen.
+
+## Environment
+
+- **Distro**: (e.g., Ubuntu 24.04)
+- **Architecture**: (e.g., x86_64 / aarch64)
+- **Session type**: (X11 / Wayland)
+- **Desktop**: (GNOME / KDE / other)
+- **OpenWhispr version**: (if already installed)
+- **Script version**: (run `head -5 setup-openwhispr.sh`)
+
+## Terminal output
+
+```
+Paste relevant output here
+```
+
+## Additional context
+
+Anything else that might help.