fix(frontend): KBSearchResultPanel uses as-any cast + duplicates KnowledgeRepository instance

[mrveiss]

Summary

Merged in #3920 (feat(frontend): KB full-text search result viewer).

Bug 1: KBSearchResultPanel.vue line ~315 casts the getDocument() result as (full as any)?.content. getDocument() already returns KnowledgeDocument with a non-optional content: string field — the cast removes TypeScript safety with no justification. Fix: use full?.content directly.

Bug 2: KBSearchResultPanel.vue line ~226 creates its own new KnowledgeRepository() instance while the parent KnowledgeSearch.vue already owns one. This causes redundant HTTP requests on every document selection. Fix: accept repository as a prop from the parent and pass the parent's existing instance.

[mrveiss]

✅ Resolved by PR #3958 — removed as-any cast and fixed duplicate KnowledgeRepository instance