feat!: move to the alpha track — DSH 0.1.2-alpha.x only (v0.18.0-alpha.0)

DSH itself is still on its 0.1.2-alpha line (npm `alpha` dist-tag), so the
plugin mirrors it: v0.18.0-alpha.0 publishes under the npm `alpha`
dist-tag and supports DSH 0.1.2-alpha.x only. Stable-DSH (0.1.0-rc.8 ~
0.1.1-rc.2) users stay on v0.17.1 (npm `latest`). Verified end-to-end
against a real 0.1.2-alpha.2 host: full vitest suite, typecheck,
build/pack, consumer type surface, and the headless mount smoke 14/14
(the prerelease version also passes `dsh plugin add file:`).

- peer floor raised `^0.1.0-rc.8` -> `^0.1.2-alpha.2` (the mount install
  no longer warns: the old floor could not semver-match a prerelease
  host); dsh.plugin.json engines.dsh `>=0.1.2-alpha.2`.
- Dropped the pre-alpha compatibility layer:
  - e2e host RPC collapsed from the dot/slash dual dialect to slash-only
    (rpcAttempt; the 404-probe negotiation and its cache are gone), and
    parseLaunchUrl now requires the ?token= launch URL;
  - MarkdownText labels collapsed to the nested single shape (the cast
    became unnecessary against the alpha.2 declarations);
  - the defunct `@deepseek-ai/dsh-client-runtime` row is gone from the
    chunk externals allowlist (chunk-loader / tsdown / two specs) and
    from dsh.client.inject.
- market-manifest guard now allows an exact prerelease version (alpha
  cuts are not the market's verified `latest` target); release.yml picks
  the npm dist-tag from the version (prerelease -> `alpha`, else
  `latest`) so an alpha can never hijack `latest`.
- Docs retargeted: AGENTS.md §2/§3, README/README_EN badges + v0.18.0
  -alpha.0 section + install note (`dsh-better-sidebar@alpha`), guide.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "dsh-better-sidebar",
-  "version": "0.17.2",
+  "version": "0.18.0-alpha.0",
   "description": "DSH web plugin: a VSCode-like right sidebar (explorer / editor / terminal / git / browser), isolated per conversation session. Exposes a service for other plugins to register sidebar tabs and file viewers.",
   "type": "module",
   "repository": {
@@ -45,7 +45,6 @@
     },
     "client": {
       "inject": [
-        "@deepseek-ai/dsh-client-runtime",
         "@deepseek-ai/dsh-client-locale",
         "@deepseek-ai/dsh-client-ui-slots",
         "@deepseek-ai/dsh-client-ui-conversation",
@@ -85,19 +84,19 @@
   "license": "MIT",
   "peerDependencies": {
     "@deepseek-ai/cordis": "^4.0.1",
-    "@deepseek-ai/dsh-agent": "^0.1.0-rc.8",
-    "@deepseek-ai/dsh-client-locale": "^0.1.0-rc.8",
-    "@deepseek-ai/dsh-client-ui-conversation": "^0.1.0-rc.8",
-    "@deepseek-ai/dsh-client-ui-primitives": "^0.1.0-rc.8",
-    "@deepseek-ai/dsh-client-ui-settings": "^0.1.0-rc.8",
-    "@deepseek-ai/dsh-client-ui-slots": "^0.1.0-rc.8",
-    "@deepseek-ai/dsh-host-webserver": "^0.1.0-rc.8",
-    "@deepseek-ai/dsh-invariants": "^0.1.0-rc.8",
-    "@deepseek-ai/dsh-llm": "^0.1.0-rc.8",
-    "@deepseek-ai/dsh-session": "^0.1.0-rc.8",
-    "@deepseek-ai/dsh-settings": "^0.1.0-rc.8",
-    "@deepseek-ai/dsh-subagent": "^0.1.0-rc.8",
-    "@deepseek-ai/dsh-tools": "^0.1.0-rc.8",
+    "@deepseek-ai/dsh-agent": "^0.1.2-alpha.2",
+    "@deepseek-ai/dsh-client-locale": "^0.1.2-alpha.2",
+    "@deepseek-ai/dsh-client-ui-conversation": "^0.1.2-alpha.2",
+    "@deepseek-ai/dsh-client-ui-primitives": "^0.1.2-alpha.2",
+    "@deepseek-ai/dsh-client-ui-settings": "^0.1.2-alpha.2",
+    "@deepseek-ai/dsh-client-ui-slots": "^0.1.2-alpha.2",
+    "@deepseek-ai/dsh-host-webserver": "^0.1.2-alpha.2",
+    "@deepseek-ai/dsh-invariants": "^0.1.2-alpha.2",
+    "@deepseek-ai/dsh-llm": "^0.1.2-alpha.2",
+    "@deepseek-ai/dsh-session": "^0.1.2-alpha.2",
+    "@deepseek-ai/dsh-settings": "^0.1.2-alpha.2",
+    "@deepseek-ai/dsh-subagent": "^0.1.2-alpha.2",
+    "@deepseek-ai/dsh-tools": "^0.1.2-alpha.2",
     "@huanlin/dsh-plugin-better-locale": "^0.1.0",
     "react": "^18.2.0",
     "react-dom": "^18.2.0"