feat: transcription log + CI/CD release pipeline

[rsslldnphy]

Summary

• Adds a persistent transcription log that records every completed dictation to ~/Library/Application Support/Wisp/transcription-log.json
• Adds a Show Log menu item that opens a SwiftUI window listing all past transcriptions with timestamps
• Adds GitHub Actions CI: runs swift test on every push to main and on PRs
• Adds GitHub Actions release pipeline: builds a .dmg and .pkg on every push to main, publishes a versioned GitHub release — .pkg is suitable for Jamf/MDM deployment

Test plan

• Open Wisp, dictate something, open Show Log — entry should appear
• Quit and relaunch — log entries should persist
• CI workflow triggers on PR and runs tests
• Release workflow triggers on merge to main and produces .dmg + .pkg artifacts

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