Add Open Studio portfolio SOTA context

[gchahal1982]

Adds Open Studio’s portfolio context as an explicitly unscored dossier, separate from the six scored product assessments.

Changes

• Rename the context document to docs/sota/open-studio-context-dossier.md.
• Cover all 13 canonical dimensions with verified context and explicit unknowns.
• State that Open Studio is unscored and receives no SOTA verdict; remove all Not Yet SOTA wording.
• Update the SOTA index to reference the canonical dossier path.

Testing

• Dossier contract check — passed: 13 dimensions, explicit unscored status, no verdict, no Not Yet SOTA, and old filename absent.
• pnpm install --frozen-lockfile — passed.
• Proofline typecheck, tests, build, and public-asset verification — passed; 40 tests.
• Aura IDE Kit typecheck, tests, and build — passed; 12 tests.
• Platform contracts typecheck/build and node --test tests/platform-contracts.test.mjs — passed.
• Registry package tests for Rubric Studio, Agent Studio, and Robotics Studio — passed.
• PATH="$HOME/.cargo/bin:$PATH" cargo test --workspace with Cargo 1.97 — passed; 44 Rust tests passed and 2 hardware/native tests were ignored.
• git diff --check — passed.
• Original untracked docs-template/.docusaurus/ and docs-template/build/ manifest — all 99 files preserved byte-for-byte.
• Independent testing subagent — attempted but failed before executing tests with: An internal error occurred. Please try again. If this issue persists, please contact support. No additional subagent verification was obtained; direct local validation and successful hosted CI remain the completed evidence.