fix(ux): better rounded tabs, x button styles + hover state

[adamleithp]

Problem

• rounded top and bottom of active tab was different
• X button in tab didn't have hover state nor triggered hover in the tab itself, making it seem broken

Changes

Active tab get's bigger rounded top

• tab button bigger rounded
  x button on tab now triggering hover state on tab itself

How did you test this code?

Locally

[greptile-apps]

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[posthog-bot]

📸 UI snapshots have been updated

1 snapshot changes in total. 0 added, 1 modified, 0 deleted:

• chromium: 0 added, 1 modified, 0 deleted (diff for shard 16)
• webkit: 0 added, 0 modified, 0 deleted

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[github-actions]

Size Change: 0 B

Total Size: 3.3 MB

ℹ️ View Unchanged

Filename	Size
frontend/dist/toolbar.js	3.3 MB

_{compressed-size-action}

[posthog-bot]

📸 UI snapshots have been updated

1 snapshot changes in total. 0 added, 1 modified, 0 deleted:

• chromium: 0 added, 1 modified, 0 deleted (diff for shard 3)
• webkit: 0 added, 0 modified, 0 deleted

Triggered by this commit.

👉 Review this PR's diff of snapshots.

[posthog-bot]

📸 UI snapshots have been updated

1 snapshot changes in total. 0 added, 1 modified, 0 deleted:

• chromium: 0 added, 1 modified, 0 deleted (diff for shard 1)
• webkit: 0 added, 0 modified, 0 deleted

Triggered by this commit.

👉 Review this PR's diff of snapshots.