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/cliff.toml

@@ -0,0 +1,40 @@
+# git-cliff configuration
+# https://git-cliff.org/docs/configuration
+
+[changelog]
+header = ""
+body = """
+{% for group, commits in commits | group_by(attribute="group") %}
+### {{ group | upper_first }}
+{% for commit in commits %}
+- {% if commit.scope %}**{{ commit.scope }}**: {% endif %}{{ commit.message | split(pat="\n") | first | trim }}{% if commit.remote.pr_number %} (#{{ commit.remote.pr_number }}){% endif %} ([#{{ commit.id | truncate(length=7, end="") }}](https://github.com/BoosApi-Desktop/BoosApi/commit/{{ commit.id }}))
+{%- endfor %}
+{% endfor %}
+"""
+footer = ""
+trim = true
+
+[git]
+conventional_commits = true
+filter_unconventional = false
+split_commits = false
+commit_preprocessors = [
+  { pattern = '\(#([0-9]+)\)', replace = "" },
+]
+commit_parsers = [
+  { message = "^feat", group = "🚀 新功能" },
+  { message = "^fix", group = "🐛 Bug 修复" },
+  { message = "^perf", group = "⚡ 性能提升" },
+  { message = "^refactor", group = "🔨 重构" },
+  { message = "^style", group = "🎨 样式" },
+  { message = "^docs", group = "📝 文档" },
+  { message = "^ci", group = "🔧 CI/CD" },
+  { message = "^chore\\(version\\)", skip = true },
+  { message = "^chore", group = "📦 杂项" },
+  { message = "^test", group = "🧪 测试" },
+  { message = "^build", group = "🏗️ 构建" },
+  { body = ".*security", group = "🔒 安全" },
+]
+filter_commits = false
+tag_pattern = "v[0-9].*"
+sort_commits = "newest"