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/libs/markstream-vue/.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,38 @@
+name: 🚀 Feature proposal
+description: Propose a feature or improvement for markstream-vue
+labels: ['enhancement: pending triage']
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for your interest in the project and taking the time to fill out this feature report!
+  - type: textarea
+    id: feature-description
+    attributes:
+      label: Description
+      description: 'What problem does this solve? Please describe the use case (AI/chat/SSE, docs, diff viewer, custom node, etc.). If you intend to submit a PR for this issue, tell us in the description. Thanks!'
+      placeholder: As a developer using markstream-vue I want [goal] so that [benefit].
+    validations:
+      required: true
+  - type: textarea
+    id: current-config
+    attributes:
+      label: Current config (if applicable)
+      description: 'Renderer props or parser options you are using (e.g., max-live-nodes, batchRendering, renderBatchSize, enableMermaid/Katex/Monaco, custom components).'
+  - type: textarea
+    id: suggested-solution
+    attributes:
+      label: Suggested solution / API shape
+      description: What would the API/prop/config look like?
+    validations:
+      required: true
+  - type: textarea
+    id: alternative
+    attributes:
+      label: Alternatives
+      description: Clear and concise description of any alternative solutions or workarounds you've considered.
+  - type: textarea
+    id: additional-context
+    attributes:
+      label: Additional context
+      description: Any other context or screenshots about the feature request here (include sample Markdown or mockups if relevant).