feat(app): sidebar improvements (pinned sessions, double click rename, hover fixes)

[Rohansguliani]

Issue for this PR

Closes #16677

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

This PR introduces several quality-of-life improvements to the sidebar session list:

1. Pinned Sessions: Users can now pin sessions to the top of the sidebar. Pin state is saved to localStorage to avoid backend schema migrations.
2. Inline Renaming: Restored the ability to double-click a session title to rename it inline (fixes the Desktop issue linked above).
3. Hover Event Fixes: Replaced pointer events with native mouse events on session items to resolve a nasty hover delay caused by HoverCard intercepting pointer states.
4. UI Cleanup: Removed redundant tooltips that popped up on hover, and added inline action buttons (Pin, Archive, Delete) directly to the session row. Also removed the outline from pinned items so they sit flush with the background.

How did you verify your code works?

Tested locally by compiling the frontend and running the backend server. Verified that pinning instantly resorts the list, double-clicking triggers the InlineEditor properly, and the hover states have zero lag.

Screenshots / recordings

@Rohansguliani - Please attach a screen recording to this PR to satisfy the UI changes compliance rule!

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Based on my search, I found one potentially related PR:

Related PR:

• feat(app): add project pinning to sidebar menu #17999 - feat(app): add project pinning to sidebar menu
  • URL: feat(app): add project pinning to sidebar menu #17999
  • Why related: This PR addresses pinning functionality in the sidebar, which overlaps with the pinned sessions feature in PR feat(app): sidebar improvements (pinned sessions, double click rename, hover fixes) #18105.

The other result (#11758) is about dynamic sidebar sorting, which is tangentially related but addresses a different concern.

Note: PR #18105 (the current PR) is the main result in most searches, which is expected since it's the active PR you're checking.

[Rohansguliani]

Direct comparison (new vs old):