feat: add hotkey system (#48)

* feat: add hotkey system for playing individual sounds

Slot-based hotkey mappings stored in ~/.config/pwsp/hotkeys.json.
Daemon serves hotkey IPC commands for CLI/compositor bindings.
GUI supports focused hotkey triggers, a dedicated Hotkeys panel
with search and conflict detection, file badges, and a key chord
capture dialog. CLI gains play-hotkey, get hotkeys, set hotkey,
set hotkey-key, and clear-hotkey subcommands.

* feat: add global hotkey support via evdev

Listen for keyboard events directly from /dev/input using evdev,
enabling hotkeys to work system-wide regardless of window focus
or display server (X11, GNOME, KDE Plasma, Hyprland).

The daemon spawns async listeners for each keyboard device at
startup, tracks modifier state, and triggers playback when a
configured chord matches. Requires the user to be in the 'input'
group; logs a warning and continues without global hotkeys if
devices are inaccessible.

* various changes

* refactor: route hotkey mutations through daemon IPC

GUI no longer writes hotkey config directly to disk. Instead, all
mutations (set slot, set key chord, clear chord, remove slot) are
sent to the daemon via IPC, which persists the changes. The state
thread periodically syncs the hotkey config back from the daemon,
so CLI-made changes are reflected in the GUI.

New IPC commands: set_hotkey_action (arbitrary action per slot),
clear_hotkey_key (remove key chord without removing the slot).

Also removes unreachable capture overlay from draw_hotkeys().

* small refactor

---------

Co-authored-by: arabian <a.tevg@ya.ru>

src/types/config.rs

@@ -1,6 +1,6 @@
-use crate::utils::config::get_config_path;
+use crate::{types::socket::Request, utils::config::get_config_path};
 use serde::{Deserialize, Serialize};
-use std::{error::Error, fs, path::PathBuf};
+use std::{collections::HashMap, error::Error, fs, path::PathBuf};
 
 #[derive(Default, Clone, Serialize, Deserialize)]
 #[serde(default)]
@@ -93,3 +93,114 @@ impl GuiConfig {
         }
     }
 }
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct HotkeySlot {
+    pub slot: String,
+    pub action: Request,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub key_chord: Option<String>,
+}
+
+#[derive(Default, Clone, Debug, Serialize, Deserialize)]
+pub struct HotkeyConfig {
+    #[serde(default)]
+    pub slots: Vec<HotkeySlot>,
+}
+
+impl HotkeyConfig {
+    pub fn config_path() -> Result<PathBuf, Box<dyn Error>> {
+        Ok(get_config_path()?.join("hotkeys.json"))
+    }
+
+    pub fn load() -> Result<HotkeyConfig, Box<dyn Error>> {
+        let path = Self::config_path()?;
+        if !path.exists() {
+            return Ok(HotkeyConfig::default());
+        }
+        let bytes = fs::read(&path)?;
+        match serde_json::from_slice::<HotkeyConfig>(&bytes) {
+            Ok(config) => Ok(config),
+            Err(_) => Ok(HotkeyConfig::default()),
+        }
+    }
+
+    pub fn save(&self) -> Result<(), Box<dyn Error>> {
+        let path = Self::config_path()?;
+        if let Some(dir) = path.parent()
+            && !dir.exists()
+        {
+            fs::create_dir_all(dir)?;
+        }
+        let json = serde_json::to_string_pretty(self)?;
+        fs::write(path, json.as_bytes())?;
+        Ok(())
+    }
+
+    pub fn find_slot(&self, slot: &str) -> Option<&HotkeySlot> {
+        self.slots.iter().find(|s| s.slot == slot)
+    }
+
+    pub fn find_slot_mut(&mut self, slot: &str) -> Option<&mut HotkeySlot> {
+        self.slots.iter_mut().find(|s| s.slot == slot)
+    }
+
+    pub fn set_slot(&mut self, slot: String, action: Request) {
+        if let Some(existing) = self.find_slot_mut(&slot) {
+            existing.action = action;
+        } else {
+            self.slots.push(HotkeySlot {
+                slot,
+                action,
+                key_chord: None,
+            });
+        }
+    }
+
+    pub fn set_key_chord(&mut self, slot: &str, key_chord: Option<String>) -> bool {
+        if let Some(existing) = self.find_slot_mut(slot) {
+            existing.key_chord = key_chord;
+            true
+        } else {
+            false
+        }
+    }
+
+    pub fn remove_slot(&mut self, slot: &str) -> bool {
+        let len = self.slots.len();
+        self.slots.retain(|s| s.slot != slot);
+        self.slots.len() != len
+    }
+
+    /// Returns pairs of slot names that share the same key chord.
+    pub fn find_conflicts(&self) -> Vec<(String, String)> {
+        let mut conflicts = vec![];
+        let mut chord_map: HashMap<&str, Vec<&str>> = HashMap::new();
+
+        for s in &self.slots {
+            if let Some(chord) = &s.key_chord {
+                chord_map.entry(chord.as_str()).or_default().push(&s.slot);
+            }
+        }
+
+        for slots in chord_map.values() {
+            if slots.len() > 1 {
+                for i in 0..slots.len() {
+                    for j in (i + 1)..slots.len() {
+                        conflicts.push((slots[i].to_string(), slots[j].to_string()));
+                    }
+                }
+            }
+        }
+
+        conflicts
+    }
+
+    /// Find which slot(s) have the given key chord.
+    pub fn slots_for_chord(&self, chord: &str) -> Vec<&HotkeySlot> {
+        self.slots
+            .iter()
+            .filter(|s| s.key_chord.as_deref() == Some(chord))
+            .collect()
+    }
+}