[DOCS]: update landing page to reflect current CLI version and features

[HoussemEddineChaouch]

What needs to be documented?

The landing page (site/index.html) is outdated and
does not reflect the current state of the CLI.

Where is the issue?

site/index.html

Suggested fix

Update the following sections:

• Hero version badge: change v1.1.1 to v1.2.0
• Tools section: add deleteFile, runCommand,
  searchWeb, appendFile cards
• Stats section: update tools count from 4 to 7
• Releases section: add v1.2.0 release card and
  remove latest badge from v1.1.1
• Demo terminal: update to show one of the new
  tools in action (e.g. runCommand or searchWeb)

References

site/index.html
github.com/HoussemEddineChaouch/mini-agent-cli/releases

[saumya-30-verma]

Hi @HoussemEddineChaouch,

I'd like to work on this issue. Could you please assign it to me? Thanks!

[HoussemEddineChaouch]

@saumya-30-verma assigned for u, looking for your PR!