Update README for 17-package workspace and current build prerequisites

[blacks1ne]

Summary

Update the root documentation to match the current 17-package workspace and its actual build prerequisites/readiness.

Current gaps

• README says “11 crates”; Cargo metadata reports 17 workspace packages.
• Newer server, WASM, diffusion, autoregressive-image, desktop, and Tauri surfaces are omitted or under-described.
• klearu-private expects ../../../monorepo/crates/ferret, but alternate monorepo layouts require a sibling symlink or path change.
• Native Ferret also requires EMP Toolkit/OpenSSL headers; a Linux check currently fails at missing emp-tool/emp-tool.h if these are not installed.
• Linux Tauri builds require WebKitGTK/JavaScriptCoreGTK 4.1 development packages.
• cargo test --workspace is currently not green because of the DDIM scheduler issue.
• Several phase comments still say backpropagation or later desktop engines are deferred even though newer implementations exist.

Proposed resolution

• Generate/maintain the workspace table from Cargo metadata.
• Add platform-specific setup sections for native private inference and Tauri.
• Distinguish unit-tested components, ignored real-model integration tests, and experimental application paths.
• Audit README commands with explicit -p and required feature flags.

Acceptance criteria

• All 17 packages are represented or intentionally grouped.
• A clean Linux/macOS setup has enough prerequisite information to reach the intended build.
• Test instructions accurately state known exclusions/failures.
• Example commands are exercised in CI at least through compilation or --help.