Feat/battery threshold (#7)

* feat(battery-threshold): add translations and rule file

* feat(battery-threshold): add setup script

* feat(battery-threshold): add plugin manifest

* feat(battery-threshold): implement battery-threshold service

* feat(battery-threshold): implement battery-threshold widget

* feat(battery-threshold): implement battery-threshold panel

* feat(battery-threshold): add readme

* chore(battery-threshold): add dependencies field

* chore(battery-threshold): add thumbnail

* docs(battery-threshold): add thumbnail to readme

* fix(battery-threshold): add thumbnail from generator

* chore(battery-threshold): add license and icon fields to plugin.toml

* style(battery-threshold): replace tabs with spaces

* style(battery-threshold): unflatten translation files

* refactor(battery-threshold): use translations for widget tooltip

* chore(battery-threshold): replace raw strings with translations

* chore(battery-threshold): remove panel ipc event

* chore(battery-threshold): check error on file read

* chore(battery-threshold): remove `setUpdateInterval` calls

* style(battery-threshold): fix formatting

* chore(battery-threshold): remove tags capital letters

* Update plugin.toml

* chore(battery-threshold): remove de fr and tr translations

* chore(battery-threshold): update thumbnail

* fix(battery-threshold): add shell quoting for runAsync

* chore(battery-threshold): embed rule file content in setup script

* chore(battery-threshold): update manifest

* refactor(battery-threshold): use noctalia.pluginDataDir, log read/write errors

* docs(battery-threshold): update README to match template

* chore(battery-threshold): add missing dependencies to manifest

---------

Co-authored-by: Lemmy <studio@quadbyte.net>

battery-threshold/README.md

@@ -0,0 +1,63 @@
+# Battery Threshold Control
+
+Control the battery charge threshold on laptop batteries to help extend overall
+battery lifespan. Someone would use this plugin to limit maximum charge levels
+while plugged in, reducing battery wear and heat.
+
+## Plugin
+
+| Field   | Value                                                               |
+| ------- | ------------------------------------------------------------------- |
+| ID      | `damian-ds7/battery-threshold`                                      |
+| Entries | Bar widget: `battery-threshold`; panel: `panel`; service: `service` |
+
+## Requirements
+
+- `polkit` - required for interactive setup
+- Laptop hardware supporting battery charge threshold control in sysfs
+  (`/sys/class/power_supply/*/charge_control_end_threshold`).
+- The following external programs must be available on `PATH`: `test`, `pkexec`,
+  `bash`, `cat`, `getent`, `groupadd`, `usermod`, `udevadm`, `chgrp`, and
+  `chmod`.
+
+## Usage
+
+- **Bar Widget (`battery-threshold`)**: Displays the current battery threshold
+  in the bar. Click to toggle the panel.
+- **Panel (`panel`)**: Adjust the battery threshold using a slider (40–100%).
+  Includes a **Configure Permissions** button if write access is missing. Toggle
+  the panel using:
+
+```sh
+noctalia msg panel-toggle damian-ds7/battery-threshold:panel
+```
+
+## Settings
+
+| Setting            | Type     | Default                        | Description                                    |
+| ------------------ | -------- | ------------------------------ | ---------------------------------------------- |
+| `battery_device`   | `folder` | `/sys/class/power_supply/BAT0` | Path to the battery sysfs directory.           |
+| `charge_threshold` | `int`    | `80`                           | Default charge threshold percentage (40–100%). |
+
+## IPC
+
+```sh
+# Set charge threshold percentage (between 40 and 100)
+noctalia msg plugin damian-ds7/battery-threshold:service all set 80
+
+# Trigger setup script for udev permissions
+noctalia msg plugin damian-ds7/battery-threshold:service all setup
+```
+
+## Notes
+
+- **Permissions & Setup**: Requires write access to
+  `/sys/class/power_supply/BAT0/charge_control_end_threshold`. Automated setup
+  creates the `battery_ctl` group, adds the active user to it, and installs
+  `99-battery-threshold.rules` to `/etc/udev/rules.d/`.
+- **Relogin / Reboot**: A logout or system reboot is required after running
+  setup for `battery_ctl` group membership changes to take effect.
+- **Manual Setup Fallback**: If Polkit is not available, run
+  `sudo ./setup_rules.sh` manually from the plugin directory.
+- **Persistence**: Threshold settings are stored in `threshold.txt` in plugin
+  directory and restored across reboots.