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/packages/markdown-parser/test/streaming-diff-fence-regression.test.ts

@@ -0,0 +1,129 @@
+import { describe, expect, it } from 'vitest'
+import { parseFenceToken } from '../src'
+
+function parseStreamingDiff(content: string, closed = false) {
+  return parseFenceToken({
+    type: 'fence',
+    info: 'diff json:package.json',
+    content,
+    map: [0, 1],
+    meta: { closed },
+  } as any)
+}
+
+describe('parseFenceToken - streaming unified diff stability', () => {
+  it('splits standard unified diff lines without requiring a space after the marker', () => {
+    const node = parseFenceToken({
+      type: 'fence',
+      info: 'diff typescript',
+      content: [
+        'diff --git a/src/render.ts b/src/render.ts',
+        'index 0000000..1111111 100644',
+        '--- a/src/render.ts',
+        '+++ b/src/render.ts',
+        '@@ -1,7 +1,12 @@',
+        '-export function render(input) {',
+        '-  return input',
+        '+export function render(input: string) {',
+        '+  if (!input.trim())',
+        '+    return \'empty\'',
+        '+',
+        '+  const normalized = input.replace(/\\r\\n/g, \'\\n\')',
+        '+  return normalized',
+        ' }',
+      ].join('\n'),
+      map: [0, 1],
+      meta: { closed: true },
+    } as any)
+
+    expect(node.language).toBe('typescript')
+    expect(node.originalCode).toBe([
+      'export function render(input) {',
+      '  return input',
+      '}',
+    ].join('\n'))
+    expect(node.updatedCode).toBe([
+      'export function render(input: string) {',
+      '  if (!input.trim())',
+      '    return \'empty\'',
+      '',
+      '  const normalized = input.replace(/\\r\\n/g, \'\\n\')',
+      '  return normalized',
+      '}',
+    ].join('\n'))
+  })
+
+  it('withholds an unfinished replacement hunk until the added side is available', () => {
+    const node = parseStreamingDiff([
+      '{',
+      '  "name": "markstream-vue",',
+      '- "version": "0.0.49",',
+    ].join('\n'))
+
+    expect(node.originalCode).toBe([
+      '{',
+      '  "name": "markstream-vue",',
+    ].join('\n'))
+    expect(node.updatedCode).toBe([
+      '{',
+      '  "name": "markstream-vue",',
+    ].join('\n'))
+  })
+
+  it('flushes a finished replacement hunk once the added line becomes stable', () => {
+    const node = parseStreamingDiff([
+      '{',
+      '  "name": "markstream-vue",',
+      '- "version": "0.0.49",',
+      '+ "version": "0.0.54-beta.1",',
+      '',
+    ].join('\n'))
+
+    expect(node.originalCode).toBe([
+      '{',
+      '  "name": "markstream-vue",',
+      '  "version": "0.0.49",',
+    ].join('\n'))
+    expect(node.updatedCode).toBe([
+      '{',
+      '  "name": "markstream-vue",',
+      '  "version": "0.0.54-beta.1",',
+    ].join('\n'))
+  })
+
+  it('withholds a trailing incomplete added line instead of leaking a mismatched preview', () => {
+    const node = parseStreamingDiff([
+      '{',
+      '  "name": "markstream-vue",',
+      '- "version": "0.0.49",',
+      '+ "version": "0.0.54-b',
+    ].join('\n'))
+
+    expect(node.originalCode).toBe([
+      '{',
+      '  "name": "markstream-vue",',
+    ].join('\n'))
+    expect(node.updatedCode).toBe([
+      '{',
+      '  "name": "markstream-vue",',
+    ].join('\n'))
+  })
+
+  it('flushes the trailing hunk once the fence is closed', () => {
+    const node = parseStreamingDiff([
+      '{',
+      '  "name": "markstream-vue",',
+      '- "version": "0.0.49",',
+    ].join('\n'), true)
+
+    expect(node.originalCode).toBe([
+      '{',
+      '  "name": "markstream-vue",',
+      '  "version": "0.0.49",',
+    ].join('\n'))
+    expect(node.updatedCode).toBe([
+      '{',
+      '  "name": "markstream-vue",',
+    ].join('\n'))
+  })
+})