test: add SmartSpeedInit focused unit test from na9

Cherry-picked from bead/audiobookshelf-na9-playerui-init (8c645cdf).

Adds focused unit test that proves Smart Speed worklet initialization
works correctly. Tests LocalAudioPlayer.setSmartSpeed() directly and
verifies audioWorklet.addModule is called with SilenceDetectorProcessor.js.

Closes audiobookshelf-na9.

client/cypress/tests/players/SmartSpeedInit.cy.js

@@ -0,0 +1,96 @@
+import LocalAudioPlayer from '../../../players/LocalAudioPlayer'
+
+describe('Smart Speed Initialization', () => {
+  it('calls audioWorklet.addModule when Smart Speed is enabled', () => {
+    const audioContext = {
+      destination: { label: 'destination' },
+      state: 'running',
+      currentTime: 0,
+      resume: cy.stub().resolves(),
+      suspend: cy.stub().resolves(),
+      close: cy.stub().resolves(),
+      createMediaElementSource: cy.stub().returns({
+        connect: cy.stub(),
+        disconnect: cy.stub()
+      }),
+      audioWorklet: {
+        addModule: cy.stub().resolves().as('audioWorkletAddModule')
+      }
+    }
+
+    cy.window().then((win) => {
+      // Create a mock audio element
+      const audioElement = win.document.createElement('audio')
+      audioElement.id = 'test-audio'
+      audioElement.src = '/__cypress/fixtures/test-audio.wav'
+      win.document.body.appendChild(audioElement)
+
+      // Mock AudioWorkletNode
+      win.AudioWorkletNode = function AudioWorkletNode() {
+        return {
+          connect: cy.stub(),
+          disconnect: cy.stub(),
+          port: {
+            onmessage: null,
+            postMessage: cy.stub()
+          }
+        }
+      }
+
+      // Create player instance
+      const player = new LocalAudioPlayer()
+      player.player = audioElement
+      player.audioContext = audioContext
+      player.usingWebAudio = true
+      player.audioSourceNode = audioContext.createMediaElementSource(audioElement)
+      player.smartSpeedRatio = 2.5
+
+      // Call setSmartSpeed with enabled=true
+      player.setSmartSpeed(true).then(() => {
+        // Verify audioWorklet.addModule was called with the correct path
+        cy.get('@audioWorkletAddModule').should('have.been.calledOnce')
+        cy.get('@audioWorkletAddModule').should(
+          'have.been.calledWith',
+          '/client/players/smart-speed/SilenceDetectorProcessor.js'
+        )
+      })
+    })
+  })
+
+  it('does not initialize worklet when Smart Speed is disabled', () => {
+    const audioContext = {
+      destination: { label: 'destination' },
+      state: 'running',
+      currentTime: 0,
+      resume: cy.stub().resolves(),
+      suspend: cy.stub().resolves(),
+      close: cy.stub().resolves(),
+      createMediaElementSource: cy.stub().returns({
+        connect: cy.stub(),
+        disconnect: cy.stub()
+      }),
+      audioWorklet: {
+        addModule: cy.stub().resolves().as('audioWorkletAddModule')
+      }
+    }
+
+    cy.window().then((win) => {
+      const audioElement = win.document.createElement('audio')
+      audioElement.id = 'test-audio'
+      audioElement.src = '/__cypress/fixtures/test-audio.wav'
+      win.document.body.appendChild(audioElement)
+
+      const player = new LocalAudioPlayer()
+      player.player = audioElement
+      player.audioContext = audioContext
+      player.usingWebAudio = true
+      player.audioSourceNode = audioContext.createMediaElementSource(audioElement)
+
+      // Call setSmartSpeed with enabled=false
+      player.setSmartSpeed(false).then(() => {
+        // Verify audioWorklet.addModule was NOT called
+        cy.get('@audioWorkletAddModule').should('not.have.been.called')
+      })
+    })
+  })
+})