refactor(admin-web): move answer markdown normalization to a tested lib

Extract normalizeLooseMarkdownLine from TrackingQuestionDetailView into
a shared monitoring-answer-markdown module and harden it (model bullet
`**-` and `*` handling). Add a vitest runner and unit tests for the
normalization rules.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

pnpm-lock.yaml

@@ -135,6 +135,9 @@ importers:
       vite-plugin-compression2:
         specifier: ^2.5.3
         version: 2.5.3(rollup@4.60.2)
+      vitest:
+        specifier: ^4.1.5
+        version: 4.1.5(@types/node@24.12.0)(vite@7.3.2(@types/node@24.12.0)(jiti@2.6.1)(lightningcss@1.32.0))
       vue-tsc:
         specifier: ^3.2.6
         version: 3.2.6(typescript@5.9.3)