Document released desktop and remote capabilities

[abrichr]

What

• document browser, Windows UIA, native macOS, native Linux AT-SPI, RDP, and Citrix/VDI across the landing, concept, onboarding, hosted, security-review, deployment-config, ecosystem, governance, and CLI reference pages
• state the managed-browser versus local/self-hosted/customer-controlled native and remote execution boundary consistently
• add exact Windows, macOS, Linux, RDP, and Citrix acceptance evidence and caveats
• select the dedicated kind: citrix / CitrixWorkspaceBackend path and document the title, frame-age, and readiness safety inputs
• update Desktop install and ecosystem guidance to the complete v0.9.0 Windows/macOS/Linux Beta release

Why

The deployed docs lag the released engine. Linux was omitted from source-of-truth matrices, RDP evidence was incomplete, Citrix was described through generic RDP in deployment configuration, and the ecosystem page still named Desktop v0.5.1.

Impact and boundaries

The docs describe Citrix confidently as implemented: exact Workspace-window binding, readiness gating, stale-frame refusal, durable resume targeting, and the shared pixel identity/effect/policy/halt contract. They preserve the decisive evidence boundary: the accepted 3 healthy + 3 drift stand-in artifact records code_readiness_accepted=true and ica_hdx_accepted=false; no counted real ICA/HDX batch is claimed.

Managed OpenAdapt Cloud remains the browser runner/control plane. Native desktop and remote workflows execute locally, self-hosted, or in customer-controlled runtimes. The branch is rebased onto current main and includes the merged account-security documentation.

Checks

• .venv/bin/python -m pytest tests/ -q — 76/76 passed
• .venv/bin/python -m mkdocs build --strict — passed
• git diff --check — passed