feat(desktop): ship Franklin Desktop 0.2 beta

[KillerQueen-Z]

Summary

• move the latest Desktop product work into the Franklin main repository as the canonical release source
• add Agent Studio, agent import/discovery, personal and Team spaces, shared projects/files, MCP, and Base/Solana wallet switching
• preserve the hardened startup window, loopback-only services, renderer/IPC boundaries, and workspace confinement
• add tag-driven macOS Apple Silicon and Windows x64 prerelease packaging with SHA-256 checksums
• set Desktop version to 0.2.0-beta.1

Validation

• npm run build
• npm run typecheck --workspace @blockrun/franklin-desktop
• npm run lint --workspace @blockrun/franklin-desktop
• npm test --workspace @blockrun/franklin-desktop
• npm run build --workspace @blockrun/franklin-desktop
• npm run dist:mac --workspace @blockrun/franklin-desktop
• packaged app isolated launch smoke test: Franklin agent, Team sidecar, and renderer all started
• DMG contents checked for the bundled Franklin runtime, Desktop renderer, startup UI, and only the required Team sidecar entry

Release notes

The installers are unsigned beta builds, so macOS and Windows may show a first-launch security prompt.

npm audit --omit=dev still reports the main Franklin dependency graph's existing 7 high-severity advisories, primarily through the Polymarket Axios and Solana bigint-buffer chains. npm currently reports no available fix for those upstream paths; this PR does not add them.