Add a framework support and limitations matrix

[achieve0410]

Problem

The README describes supported React, Vue, Nuxt, and Django patterns in prose, but contributors and evaluators cannot scan one grounded matrix to distinguish recognized patterns from explicit Unresolved or out-of-scope behavior.

Scope

Add one compact support matrix to README.md or a linked document. This is documentation-only; it must describe the current implementation rather than broaden it.

Acceptance criteria

• cover React Router v6 JSX/data routes, Vue 3 SFC routes, Nuxt 3+ file-based pages and request/navigation APIs, and recognizable Django URL/view/helper/model/ORM structure
• distinguish supported, terminal boundary, explicitly Unresolved, and out-of-scope cases
• include Nuxt server/api terminal behavior and the current layouts/middleware limitation
• ground each material claim in an existing test, docs/graph-contract.md, or docs/security-model.md
• avoid exhaustive-discovery language and do not introduce new graph metadata or evidence categories
• keep the README concise by linking detailed contract material instead of duplicating it

Verification

• cross-check the matrix against the current fixture and test suite
• run documentation-relevant checks and report any validation gap