docs: overhaul mcp docs (#1927)

Stremline the prose for clarity & conciseness
Remove outdated SSE section
Restructure the content
Adjusted description in frontmatter

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Restructures MCP docs with tabbed OAuth/Bearer client configs (Cursor,
VS Code, Claude), adds tool selection and advanced/troubleshooting
sections, updates links/frontmatter, and removes legacy SSE guidance.
> 
> - **Docs restructuring and content**:
> - **Authentication & setup**: Introduce tabbed configs for OAuth and
Bearer token; add client-specific setup for `Cursor`, `VS Code`, and
`Claude Desktop` using `Tabs`.
> - **Quick start split**: Clarify hosted Streamable HTTP vs local stdio
with updated examples and config snippets.
> - **Tool selection**: Explain `tools` query/CLI flags with minimal and
default examples; add UI configurator link.
> - **Available tools**: Refresh table; add `get-actor-output` tool and
note on retrieving full outputs.
> - **Advanced/troubleshooting**: Add production best practices, rate
limits/performance, and troubleshooting (auth, local env, actor issues).
> - **Removals/cleanups**:
>   - Remove legacy SSE transport section and related examples.
> - **Metadata and links**:
>   - Update frontmatter description and add `toc_max_heading_level: 4`.
>   - Update images/prose and GitHub links to `apify/apify-mcp-server`.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
71640ce. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

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Co-authored-by: Jakub Kopecký <[email protected]>
Co-authored-by: Jiří Spilka <[email protected]>

Author: 3 people