feat: support dsh 0.1.7-rc.1 as the supported V4 line

Every runtime seam the plugin rides is source-identical from
0.1.7-alpha.2, so no code changes; the supported V4 baseline moves
from 0.1.7-alpha.2 to 0.1.7-rc.1 (the alphas leave the matrix). rc.1
adds the harness-side plugin peer-compatibility admission gate
(evaluatePluginCompatibility); the plugin's >=0.1.2-rc.1 dsh peers
satisfy it under the gate's includePrerelease check, so the bundle
composes with no exemption. The release workflow fetches the rc.1 tag
for the compat matrix and points the plugin checker at the npm next
dist-tag (0.1.7-rc.1).

.github/workflows/release.yml

@@ -19,7 +19,7 @@ jobs:
       - uses: actions/checkout@v7
 
       - name: Check the DeeSeek Harness plugin
-        # `alpha` = the newest published generation (0.1.7-alpha.1), whose npm
+        # `next` = the newest published generation (0.1.7-rc.1), whose npm
         # dependency closure is complete. The 0.1.5-rc `latest` line is
         # transitively broken on npm right now: web-app 0.1.5-rc.3 was
         # published without the dsh-client-ui-sidebar-documentpreview rc.3 it
@@ -27,7 +27,7 @@ jobs:
         # upstream republishes a complete stable closure.
         uses: bowenliang123/dsh-plugin-checker@v1
         with:
-          dshVersion: alpha
+          dshVersion: next
 
       # Reads the pinned pnpm version from `packageManager` in package.json.
       - uses: pnpm/action-setup@v6
@@ -65,7 +65,7 @@ jobs:
             refs/tags/dsh-v0.1.2-rc.1:refs/tags/dsh-v0.1.2-rc.1 \
             refs/tags/dsh-v0.1.3-alpha.2:refs/tags/dsh-v0.1.3-alpha.2 \
             refs/tags/dsh-v0.1.5-rc.1:refs/tags/dsh-v0.1.5-rc.1 \
-            refs/tags/dsh-v0.1.7-alpha.2:refs/tags/dsh-v0.1.7-alpha.2
+            refs/tags/dsh-v0.1.7-rc.1:refs/tags/dsh-v0.1.7-rc.1
 
       - name: Test
         run: DSH_REPO="$PWD/.tmp/dsh-repo" pnpm test