Docs: Clarify GAIA's identity and audience paths across README, docs site, and quickstart

[itomek-amd]

Summary

As GAIA has grown to include the Agent UI, Python SDK, and C++ framework, the documentation can be improved to more clearly communicate what GAIA is, what it enables, and which entry point best fits a given user. This is an opportunity to sharpen the messaging across the README, docs site, and quickstart now that the project spans multiple audiences and install paths.

Areas where the documentation could be clearer:

• The relationship between GAIA as a product and its components (Agent UI, Python SDK, C++ framework) isn't immediately obvious — it's easy to conflate GAIA with one of its parts
• The README leads with SDK messaging and a Python code example, but the quickstart opens with an npm install for the Agent UI, creating a disconnect between the two surfaces
• The docs site is titled "GAIA SDK," which doesn't fully represent the Agent UI or C++ framework paths
• The Python/C++ split already introduces a fork in the docs; layering the npm-based Agent UI on top adds a third dimension that would benefit from clearer signposting
• Lemonade Server's role as the inference layer is referenced but not explained — the component boundaries (GAIA → Lemonade → inference engine → model) aren't made explicit

Suggestion

Consider restructuring the top-level documentation to surface the audience paths up front. For example:

• "I want to use AI locally" → Agent UI (npm install, zero code)
• "I want to build AI agents in Python" → Python SDK (pip install, code examples)
• "I want to embed agents in native apps" → C++ Framework (cmake, no Python dependency)

Each path should briefly explain the full stack so users can understand the component boundaries from a single page.

Acceptance Criteria

• The README and docs landing page clearly describe what GAIA is and what it enables in terms accessible to a general audience
• A user can identify which install path (npm / pip / cmake) matches their use case without navigating multiple pages
• The relationship between GAIA, Lemonade Server, and the underlying models is explained at the top level
• The docs site title and navigation accurately reflect the full scope of the project (UI, Python SDK, C++ framework)