v0.4.0 — Fix streaming, auth, theming & dialogs

Fixes

• Chat streaming (CRITICAL): Messages now accumulate properly instead of showing only the last token
• Assistant text color: Readable on both light and dark themes (was invisible on light)
• Auth handling: Tailscale/local mode no longer sends hardcoded token
• Connect params: Mode changed from ui to operator, version from BuildConfig
• Session rename dialog: No longer targets wrong session after context menu dismissal
• Version display: Settings shows actual build version instead of hardcoded v0.3.0
• Error logging: WebSocket failures now include HTTP status codes
• Build: targetSdk 34→35, versionCode 11