Update walkthrough

[sergeibbb]

Description

Solves #4846 (PLG-121)

Checklist

• I have followed the guidelines in the Contributing document
• My changes follow the coding style of this project
• My changes build without any errors or warnings
• My changes have been formatted and linted
• My changes include any required corresponding changes to the documentation (including CHANGELOG.md and README.md)
• My changes have been rebased and squashed to the minimal number (typically 1) of relevant commits
• My changes have a descriptive commit message with a short title, including a Fixes $XXX - or Closes #XXX - prefix to auto-close the issue that your PR addresses

[sergeibbb]

@copilot please review changes of this PR and add a CHANGELOG note linked to #4842

[Copilot]

@sergeibbb I've opened a new pull request, #4845, to work on those changes. Once the pull request is ready, I'll request review from you.

[sergeibbb]

One thing I concerned here about is that I could delete too much.

The visualized result of these changes is in this comment in Jira:

cc @eamodio @axosoft-ramint @d13

[augmentcode]

🤖 Augment PR Summary

Summary: This PR refreshes the GitLens Welcome walkthrough to streamline onboarding and better highlight core features.

Changes:

• Updates the “Welcome” walkthrough step copy (titles/descriptions) and reorders/reshapes steps (Graph, AI/Composer, Inline Blame, Launchpad/Worktrees)
• Removes older walkthrough steps/content (Home View, Integrations, Streamline Collaboration) and adds a new Inline Blame walkthrough markdown asset
• Updates walkthrough thumbnails (migrating some images from .jpg to .png)
• Adds a new walkthrough command to open the Composer and emits matching walkthrough action telemetry
• Extends walkthrough completion tracking to include a new “generate commits” usage action for AI features
• Updates telemetry event documentation and related TypeScript telemetry constants to reflect renamed/removed walkthrough actions/context keys
• Adds an Unreleased changelog note describing the updated walkthrough

Technical Notes: Introduces an action:…:happened usage key to mark non-command actions for walkthrough completion (e.g., AI commit generation from the Composer webview).

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[augmentcode]

Review completed. 1 suggestions posted.

Comment augment review to trigger a new review at any time.

[axosoft-ramint]

One comment about sending through source for telemetry.

[axosoft-ramint]

Please send the walkthrough as a source here. All the composer telemetry needs it.

[sergeibbb]

@axosoft-ramint

Fixed

[axosoft-ramint]

I don't have the context needed to do anything here besides a code scan for technical issues, but having found no other issues, LGTM