feat: 10-band EQ, connection indicator, new icon (v1.5.0)

### 10-Band Graphic Equalizer
- Full EQ in Rust audio engine via EqSource<S> biquad peak filters
- 10 built-in presets + custom preset save/delete
- EqSource::try_seek() implemented — also fixes waveform seek which broke
  silently when EQ was introduced (rodio returned SeekError::NotSupported)
- EQ state persisted in localStorage, synced to Rust on startup

### Connection Indicator
- LED in header (green/red/pulsing) with server name and LAN/WAN label
- Offline overlay with retry button when server is unreachable
- useConnectionStatus hook

### New App Icon
- New logo (logo-psysonic.png) applied across Login, Sidebar, Settings,
  README and all Tauri platform icons (Windows, macOS, Linux, Android, iOS)

### Now Playing Page
- New /now-playing route added

### Fixes
- WaveformSeek: mousemove/mouseup on window to fix drag outside canvas

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src-tauri/Cargo.lock

@@ -271,6 +271,15 @@ dependencies = [
  "syn 2.0.117",
 ]
 
+[[package]]
+name = "biquad"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "820524f5e3e3add696ddf69f79575772e152c0e78e9f0370b56990a7e808ec3e"
+dependencies = [
+ "libm",
+]
+
 [[package]]
 name = "bitflags"
 version = "1.3.2"
@@ -2164,6 +2173,12 @@ dependencies = [
  "windows-link 0.2.1",
 ]
 
+[[package]]
+name = "libm"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7fc7aa29613bd6a620df431842069224d8bc9011086b1db4c0e0cd47fa03ec9a"
+
 [[package]]
 name = "libredox"
 version = "0.1.14"
@@ -3118,8 +3133,9 @@ dependencies = [
 
 [[package]]
 name = "psysonic"
-version = "1.4.5"
+version = "1.5.0"
 dependencies = [
+ "biquad",
  "reqwest 0.12.28",
  "rodio",
  "serde",
@@ -3132,6 +3148,7 @@ dependencies = [
  "tauri-plugin-notification",
  "tauri-plugin-shell",
  "tauri-plugin-store",
+ "tauri-plugin-window-state",
  "tokio",
 ]
 
@@ -4580,6 +4597,21 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "tauri-plugin-window-state"
+version = "2.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "73736611e14142408d15353e21e3cca2f12a3cfb523ad0ce85999b6d2ef1a704"
+dependencies = [
+ "bitflags 2.11.0",
+ "log",
+ "serde",
+ "serde_json",
+ "tauri",
+ "tauri-plugin",
+ "thiserror 2.0.18",
+]
+
 [[package]]
 name = "tauri-runtime"
 version = "2.10.1"