chore(release): M137 版本升到 0.2.1，发布只发两个 Windows 槽位

版本：`[workspace.package] version` 0.2.0 → 0.2.1，并把全部 intra-workspace path
依赖的 version 约束一并对齐（`"0.2"` → `"0.2.1"`，M121 的教训）。Cargo.lock 里只有
8 个 unlucky-* 成员条目变化。`crates/app` 是 workspace `exclude` 的 Slint 退役树（manifest
连解析都过不了），不参与解析，故原样保留。

release.yml：新增 `PUBLISH_SLOTS` 白名单（唯一开关）＝ `windows-x64 windows-arm64`。
六槽位一律构建取证，release job 先按白名单裁掉 Linux/macOS 四档产物再重算 SHA256SUMS，
所以 tag 触发的 Release 只有 4 个资产 + SHA256SUMS.txt。release job 改成
`always() && !cancelled()`：未验证槽位构建失败不连坐 Windows 发布，真正的门禁是白名单
齐全性检查。将来某槽位真机验过后把它加进那一行即打开。

顺手修掉一处从未生效的门禁：齐全性检查的 glob 用的是连字符形态
（`dist/$prefix-*-$slot*`），对 D49 之后的下划线资产名永远匹配不上，改成
`dist/${prefix}_*_${stem}*`。资产命名规则 / SHA256SUMS / 合规文本并列资产 /
`--version` 与 tag 交叉校验一律未动。

packaging/release-notes.md：清掉 v0.1.0 / Slint 时代的说明，Downloads 与 Support matrix
只描述本版实际发布的 Windows 两个槽位（其余标「built by CI, not published」）。
packaging/README.md §1/§3/§9 同步 gate（矩阵加「本版发布」列、§3 写清白名单与打开办法）。
起手顺带把示例 tag 从 v0.2.0 更到 v0.2.1，并把「winit / femtovg」更正为「winit / wgpu」。

Cargo.lock

@@ -4982,7 +4982,7 @@ checksum = "ca718471876992059f251e33aafc334346ada08042b7661dd1fe313a9bced557"
 
 [[package]]
 name = "unlucky-agent"
-version = "0.2.0"
+version = "0.2.1"
 dependencies = [
  "axum",
  "futures-util",
@@ -4997,7 +4997,7 @@ dependencies = [
 
 [[package]]
 name = "unlucky-app-iced"
-version = "0.2.0"
+version = "0.2.1"
 dependencies = [
  "iced",
  "image",
@@ -5010,7 +5010,7 @@ dependencies = [
 
 [[package]]
 name = "unlucky-cli"
-version = "0.2.0"
+version = "0.2.1"
 dependencies = [
  "serde",
  "serde_json",
@@ -5021,7 +5021,7 @@ dependencies = [
 
 [[package]]
 name = "unlucky-core"
-version = "0.2.0"
+version = "0.2.1"
 dependencies = [
  "flate2",
  "futures-util",
@@ -5040,15 +5040,15 @@ dependencies = [
 
 [[package]]
 name = "unlucky-design"
-version = "0.2.0"
+version = "0.2.1"
 
 [[package]]
 name = "unlucky-i18n"
-version = "0.2.0"
+version = "0.2.1"
 
 [[package]]
 name = "unlucky-palette-extract"
-version = "0.2.0"
+version = "0.2.1"
 dependencies = [
  "image",
  "unlucky-design",
@@ -5056,7 +5056,7 @@ dependencies = [
 
 [[package]]
 name = "unlucky-presenter"
-version = "0.2.0"
+version = "0.2.1"
 dependencies = [
  "serde",
  "serde_json",