left_sidebar: Show tooltip only for truncated channel names.

[userAdityaa]

This commit replaces the default HTML title attribute with a Tippy.js tooltip for stream names in the subscription block, ensuring that tooltips are shown only when the name is truncated.

Fixes #31807

Before(Big Channel name)	After(Big Channel name)

Before(Small Channel name)	After(Small Channel name)

This tooltip only shows when the stream name is big such that it will get truncated.

Self-review checklist

• [x] Self-reviewed the changes for clarity and maintainability (variable names, code reuse, readability, etc.).

Communicate decisions, questions, and potential concerns.

• [ ] Explains differences from previous plans (e.g., issue description).
• [ ] Highlights technical choices and bugs encountered.
• [ ] Calls out remaining decisions and concerns.
• [ ] Automated tests verify logic where appropriate.

Individual commits are ready for review (see commit discipline).

• [ ] Each commit is a coherent idea.
• [ ] Commit message(s) explain reasoning and motivation for changes.

Completed manual review and testing of the following:

• [x] Visual appearance of the changes.
• [x] Responsiveness and internationalization.
• [ ] Strings and tooltips.
• [ ] End-to-end functionality of buttons, interactions and flows.
• [ ] Corner cases, error conditions, and easily imagined bugs.

[zulipbot]

Hello @zulip/design members, this pull request was labeled with the "redesign" label, so you may want to check it out!

[alya]

Your screenshots should also demonstrate that there's no tooltip for a short channel name. Thanks!

[userAdityaa]

Hey @alya, Ready for review.

[alya]

Please updated your commit message: "streams" are called "channels" now, and you're missing a period.

[userAdityaa]

Ready for review!

[alya]

@sayamsamal can you review this one? I haven't tested.

[sayamsamal]

Also, the prefix of the PR title could be more concise, and it shows the area on which you have worked on. Some thing like left_sidebar or tooltips would be appropriate over here.

[userAdityaa]

Hey, How is this test failing just after changing the variable name.

[sayamsamal]

@userAdityaa if you take a look at https://github.com/zulip/zulip/actions/runs/11439296839/job/31822666704?pr=32075#step:16:1181, where I ran the Puppeteer tests to confirm the problem you were facing, you'll notice that the error is with the selector: .stream-name[title="Verona"] since you are removing the title attribute from the element.

[userAdityaa]

Thanks for the help @sayamsamal.

[userAdityaa]

@sayamsamal, Can you please check this once now ?

[sayamsamal]

I also don't see any comments replying to https://github.com/zulip/zulip/pull/31851#discussion_r1811103470.

[userAdityaa]

I also don't see any comments replying to #31851 (comment).

I forgot to reply to it. Sorry, my mistake.

[userAdityaa]

Hey @sayamsamal, I'm confused with the error in the test failure. Can you please help me with this ?

[timabbott]

There's a known puppeteer test failure in main; see chat.zulip.org for details.

[sayamsamal]

Other than the one comment, the PR LGTM. I'll mark it for integration once you remove the irrelevant whitespace changes.

[timabbott]

Closing, as this needs to be reworked to address https://github.com/zulip/zulip/pull/31851#discussion_r1857009686.