feat(mcp): kebab__search filter inputs (fb-36)

7 new optional inputs on SearchInput: tags, lang, path_glob,
trust_min, media, ingested_after, doc_id. Validation surfaces as
error.v1 code = invalid_input via StructuredError. Dispatch builds
SearchFilters from the inputs and forwards through the existing
search_with_opts_with_config facade.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/kebab-mcp/tests/tools_call_fetch.rs

@@ -62,6 +62,13 @@ async fn fetch_tool_chunk_returns_fetch_result_v1() {
             max_tokens: None,
             snippet_chars: None,
             cursor: None,
+            tags: None,
+            lang: None,
+            path_glob: None,
+            trust_min: None,
+            media: None,
+            ingested_after: None,
+            doc_id: None,
         },
     );
     let search_text = match &search_result.content.first().unwrap().raw {