fix(review): validate skill roots at mount and isolate provider default roots

ds-review-bot round 1 on the repository-plugin runtime:
- a manifest-declared skill root absent or non-directory in the installed
  package now fails the plugin load (skill-local treats a missing root as
  legitimately empty, which silently mounted a skill-less plugin)
- includeDefaultRoots: false no longer inherits $DSH_BUNDLED_SKILL_DIR, so
  isolated repository providers see only their explicit roots
- prepared wrapper baseUrl schema requires the file: scheme, failing hostile
  URLs at the declared validation boundary
- preparedPath reuses format.ts's isOutside; SERVER_NAME_PATTERN is exported
  and pinned equal to dsh-mcp-client's, with the restatement justified (the
  prepare bin keeps a zod-only module graph); the unexplained `as never`
  cast now carries its schemastery rationale
- the import-free wrapper assertion also rejects dynamic import(
- the headless fixture wrapper is regenerated by the real prepareDshPlugin
  and a drift test pins fixture == generator output
- prepareDshPlugin JSDoc states the non-atomic publish repair contract

.agents/notes/implemented/architecture/2026-07-30-static-repository-plugin-format.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/architecture/2026-07-30-static-repository-plugin-format.md
-2026-07-30-static-repository-plugin-format.md: c4739a6843db515d4cd67441e74bbf05228c612a
-2026-07-30-static-repository-plugin-format.zh.md: 0b0a2af132137a820ba941869a612b7f28754fcb
+2026-07-30-static-repository-plugin-format.md: f31728e28ddbb8e6403f327cb5b7c7533b214129
+2026-07-30-static-repository-plugin-format.zh.md: ec2295579353632a605aeb4eb2da7a39cfc4b23a