feat(desktop): embed BoosAPI Desktop client as a subproject

Vendor the rebranded BoosAPI Desktop client (Tauri + Vue) into metapi as
a monorepo subdirectory under desktop/. Source only — node_modules,
dist, Cargo target and the upstream .git history are excluded.

desktop/ keeps its own independent Cargo workspace (desktop/src-tauri
with crates/*); it is not part of the backend boosapi crate, so a
`cargo check` at the metapi root still compiles only the backend. Build
the desktop app from desktop/src-tauri per desktop/README.md.

Note: app icons are still placeholder assets pending the final BoosAPI
logo. The updater signing keys live outside the repo and are not
included.

desktop/.gitignore

@@ -0,0 +1,55 @@
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+lerna-debug.log*
+
+node_modules
+dist
+dist-ssr
+*.local
+.superpowers
+.vscode
+.agents
+.mcp.json
+
+# Editor directories and files
+.vscode/*
+!.vscode/extensions.json
+.idea
+.DS_Store
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?
+
+# Build outputs
+dist/
+target/
+
+# Secrets
+*.key
+
+# Planning files
+task_plan.md
+findings.md
+progress.md
+docs/superpowers/*
+
+# Local git worktrees
+.worktrees/
+
+# Website (VitePress)
+website/node_modules/
+website/docs/.vitepress/cache/
+website/docs/.vitepress/dist/
+fix/
+autoresearch-*.json
+research-*.tsv
+.autoresearch/
+
+debug/*