Add Privacy/Terms link to Sign in page

[matmanna]

While already linked in the hackatime landing page's footer, I think this makes it clearer at the time of authentication that Hackatime is considered a "Hack Club Service" per the Privacy Policy / Terms and Conditions. This also matches how HCA presents this link in its own auth pages.

Before:

After:

[greptile-apps]

Greptile Summary

This PR makes two small UI changes to the sign-in page: it updates the subtitle copy from "coding time" to "hacking time," and adds a privacy policy/terms consent notice that links to https://hackclub.com/privacy — matching the pattern used by HCA's own auth pages.

• The new privacy link is a sensible UX addition that aligns with Hack Club's broader policy presentation.
• The subtitle wording change ("coding" → "hacking") fits the Hack Club brand voice.
• The new <p> element has a minor indentation inconsistency (6 spaces vs. 4) relative to its sibling elements, and wrapping it in a <div class="text-center"> (like the "Back to home" link above) would keep text alignment consistent.
• No functional logic, data flows, or backend code was changed — this is a purely cosmetic UI update, so no tests are required.

Confidence Score: 5/5

• This PR is safe to merge — it's a purely cosmetic UI change with no logic, security, or data concerns.
• Only one file was changed with two straightforward additions: a copy tweak and a static privacy link. The sole issue (indentation/text-center) is a non-blocking style nit that doesn't affect functionality.
• No files require special attention.

Important Files Changed

Filename	Overview
app/javascript/pages/Auth/SignIn.svelte	Adds a privacy policy/terms link at the bottom of the sign-in page and changes "coding" to "hacking". Minor indentation inconsistency on the new paragraph element.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[User visits /sign_in] --> B[SignIn.svelte renders]
    B --> C[Logo + Title + Subtitle]
    C --> D[AuthForm: HCA / Slack / Email]
    D --> E["← Back to home link"]
    E --> F["✨ NEW: Privacy policy & terms link\n(https://hackclub.com/privacy)"]

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Prompt To Fix All With AI

This is a comment left during a code review.
Path: app/javascript/pages/Auth/SignIn.svelte
Line: 88-90

Comment:
**Indentation inconsistency**

The new `<p>` element is indented with 6 spaces, while its sibling `<div class="text-center">` elements are at 4 spaces. It also should probably be wrapped in a `text-center` div (or have `text-center` on the `<p>` itself) for consistency with the rest of the page, since the parent flex container's `items-center` only centers the block, not the text within it.

```suggestion
    <div class="text-center">
      <p class="text-secondary text-sm">
        By signing in, you agree to the Hack Club <a class="text-primary" href="https://hackclub.com/privacy">privacy policy and terms</a>.
      </p>
    </div>
```

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (1): Last reviewed commit: "feat: add privacy&terms warning to signi..." | Re-trigger Greptile}