feat(keyboard_locks): add Caps/Num/Scroll lock indicators

[noirbizarre]

Summary

Adds a new bar module displaying Caps/Num/Scroll Lock state, with click-to-toggle support.

• Reads LED state from /dev/input/event* via evdev (compositor-agnostic — works on both Hyprland and Niri).
• Hotplug-aware via a udev monitor on the input subsystem.
• Clicking an indicator toggles the corresponding lock through a lazily-created /dev/uinput virtual keyboard. If /dev/uinput cannot be opened, the display still works and clicks become no-ops with a single warning.
• Per-lock config: enabled, visibility (ActiveOnly default / AlwaysVisible), and an optional icon override (Nerd Font glyph or plain text). Default glyphs bundled (no extra font install required).
• Module renders the three indicators flush inside a single rounded island (no inner pill rounding), each with a per-icon hover highlight that matches the rest of the bar.

Permissions

Both /dev/input/event* and /dev/uinput are typically owned by the input group, so a single sudo usermod -aG input \"\$USER\" is enough. The user docs cover the manual udev-rule fallback for systems where /dev/uinput is not in the input group by default.

Testing

• make check (fmt + cargo check + clippy -D warnings) is clean.
• Verified manually with bar_style = \"Islands\" and all three locks set to AlwaysVisible: glyphs render flush inside one island, click toggles the corresponding lock, LED state updates after the kernel synthesizes the press.
• Verified that without /dev/uinput access the display still updates from external lock presses; clicks log a single warning and no-op.

Docs

website/docs/configuration/modules/keyboard.md adds a new "Keyboard Locks" section. Versioned docs under website/versioned_docs/ are untouched per the project policy.

Screenshots

Notes

• I've been using it until now without any issue.
• I've been using AI to code this, I prefer to be transparent on this (and hope this is not an issue)