feat: add RichInstallerReporter and deprecate show_progress

[ritankarsaha]

Description

Summary

Follow-up to #2187. The InstallerReporter is a @runtime_checkable Protocol, this PR ships a first-party rich-powered implementation so users get a beautiful live progress display without writing their own reporter.

#2187 (review) addressed this comment and implemented this properly
@baszalmstra

This PR implements a ready-to-use InstallerReporter backed by rich that renders three stacked live panels:

  │      Panel      │                                   Content                                   │
  ├─────────────────┼─────────────────────────────────────────────────────────────────────────────┤
  │ Overall         │ Transaction progress bar — packages done / total with ETA                   │
  ├─────────────────┼─────────────────────────────────────────────────────────────────────────────┤
  │ Downloads       │ One transient bar per active download with bytes, speed, and time remaining │
  ├─────────────────┼─────────────────────────────────────────────────────────────────────────────┤
  │ Links / Unlinks │ One transient spinner row per active link or unlink operation               │
  └─────────────────┴─────────────────────────────────────────────────────────────────────────────┘

Also raises a clear ImportError with install instructions when rich is not available.

Before

  await install(records, prefix)

After

  from rattler.install import RichInstallerReporter
  await install(records, prefix, reporter=RichInstallerReporter())

RichInstallerReporter is re-exported from both rattler.install and the top-level rattler package.

How Has This Been Tested?

• Manual: pip install py-rattler[rich] and run an install verify the three live panels render
• Manual: without rich installed, RichInstallerReporter() raises ImportError with instructions
• Manual: install(records, prefix) without reporter emits DeprecationWarning

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added sufficient tests to cover my changes.

@baszalmstra

[ritankarsaha]

#2187 (review) @baszalmstra addressed comment in this PR in follow up to #2187

Can you please take a look if any more modifications or changes are required here?

[baszalmstra]

Remove this line.

[baszalmstra]

Can you record a little GIF that shows what this now looks like when installing an environment?

[ritankarsaha]

@baszalmstra is this okaay? I made this using vhs, do you require the demo.tape file ? Let me know if you need anything else from my side.
Also addressed your reviews but added them, because show_progress and reporter co exist, should I then remove show_progress entirely ? Let me know what would be the best approach for this properly. For now made the changes you asked for and pushing in a new commit.

[ritankarsaha]

@baszalmstra ^^

[ritankarsaha]

@baszalmstra are there any more changes which are required to this ?