Add Gemini Sidebar Applet

[bhuveevh]

This PR adds the Gemini Sidebar Applet (gemini-sidebar@bhuvee).
It creates a responsive 20% width panel on the right side of the primary screen to load Google Gemini smoothly with dark theme sync and session persistence.

[github-actions]

Best-practices scanner

This is a regex-based check for API usage that can pose security, performance or
maintainability issues, or that may already be provided by Cinnamon. Most findings
are advisory and do not automatically disqualify a pull request.

This check is not perfect and will not replace a normal review.

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Found 1 potential issue(s):

ℹ️ INFO

ℹ️ shell_string_spawn

gemini-sidebar@bhuvee/applet.js:24

Util.spawnCommandLine(this.applet_path + "/gemini_sidebar.py");

Prefer argument vector spawn functions over shell command strings.
This is especially important when arguments include untrusted input (user data,
filenames, settings values, etc.) as shell strings are vulnerable to injection.
Static command strings are generally fine, but argv is always safer.
Use Util.spawn(["cmd", "arg1", "arg2"]) or Util.trySpawn() instead.

---

Automated pattern check.

[github-actions]

Best-practices scanner

This is a regex-based check for API usage that can pose security, performance or
maintainability issues, or that may already be provided by Cinnamon. Most findings
are advisory and do not automatically disqualify a pull request.

This check is not perfect and will not replace a normal review.

---

Found 1 potential issue(s):

ℹ️ INFO

ℹ️ shell_string_spawn

gemini-sidebar@bhuvee/applet.js:24

Util.spawnCommandLine(this.applet_path + "/gemini_sidebar.py");

Prefer argument vector spawn functions over shell command strings.
This is especially important when arguments include untrusted input (user data,
filenames, settings values, etc.) as shell strings are vulnerable to injection.
Static command strings are generally fine, but argv is always safer.
Use Util.spawn(["cmd", "arg1", "arg2"]) or Util.trySpawn() instead.

---

Automated pattern check.

[claudiux]

Please respect the File Structure