Enhancement: Unified UX Audit and UI fixes for Analytics workflow

Feature request

##Is your feature request related to a problem?
Yes. Currently, the "Insight-to-Dashboard" flow contains several UX friction points that lead to cognitive load and "Dashboard Graveyards." Specific issues include:

Ambiguous Feedback: Users are unsure if an insight was successfully saved due to lack of redirection and non-semantic notification colors (Green used for both "Add" and "Remove").

High Interaction Cost: Saving and viewing an insight requires multiple manual steps and repetitive navigation.

Low Visual Affordance: Insight types (Trend, Funnel, Retention) use identical button styles, forcing users to read text instead of recognizing icons.

Passive Empty States: The "Dashboard empty" state doesn't provide a clear path to action for new users.

##Describe the solution you'd like
I propose a series of UI improvements to streamline the core analytics journey:

Split-Button "Save & View": A primary purple button that saves the insight and automatically redirects the user to the destination dashboard.

Semantic Notifications: Use distinctive colors for toast messages (e.g., Amber/Neutral for "Removed" actions) to prevent mapping errors.

Unique Visual Identifiers: Apply unique icons and subtle brand colors to Trend, Funnel, and Retention buttons to aid rapid identification.

Actionable Dashboards: Replace passive illustrations with "Quick Start" template buttons directly in empty states.

Visual Previews: Add mini-sparklines/thumbnails in the "Add to dashboard" modal for faster insight identification.

##Describe alternatives you've considered
Full UI Redesign: Dismissed due to high engineering effort. The proposed changes offer a higher Impact/Effort ratio.

In-app Guided Tours: While helpful, they don't fix the underlying friction in the UI elements themselves. Improving the "Affordance" of buttons is a more scalable solution.

##Additional context
Based on a UX Audit including self-testing and community sentiment analysis (Reddit/YouTube 2025-2026).

I have detailed wireframe concepts and JTBD mapping for these points if the team is interested in discussing these further!

link of Figjam:
https://www.figma.com/board/iDRGCqwNhfRbK0PkXXU1h5/PostHog?node-id=0-1&t=WRB52m1hKXdMemdn-1

Debug info

- [ ] PostHog Cloud, Debug information: [please copy/paste from https://us.posthog.com/settings/project-details#variables]
- [ ] PostHog Hobby self-hosted with `docker compose`, version/commit: [please provide]
- [ ] PostHog self-hosted with Kubernetes (deprecated, see [`Sunsetting Kubernetes support`](https://posthog.com/blog/sunsetting-helm-support-posthog)), version/commit: [please provide]