Stop sending voice transcripts and AI responses to PostHog

[sat-sat]

Problem

trackUserMessageSent and trackAIResponseReceived in ClickyAnalytics.swift
were sending the full verbatim text of every user voice transcript and every
Claude response to PostHog. For an app that captures screen and voice, users
reasonably expect that conversation content stays on their device.

Fix

Remove the transcript and response properties from the two analytics events.
The character_count property is retained in both — this preserves useful usage
metrics (response length trends, input length) without exposing any content.

Changes

• ClickyAnalytics.swift: remove "transcript" from user_message_sent event
• ClickyAnalytics.swift: remove "response" from ai_response_received event

[sat-sat]

Hey @farzaa — just curious, was there a specific reason for sending full transcripts and responses to PostHog? Given that Clicky has access to the user's screen and voice, I think keeping conversation content off third-party servers is important for user trust. If there's specific analytics signal you were hoping to get from the content, let me know and I'm happy to add something more privacy-preserving to this PR.