fix(mcp): expose wiki output in structured content - #3590

Description

MCP clients that only inspect structuredContent currently receive Wiki routing metadata but not the page/search body. The Wiki MCP handlers pass the body only as the text fallback while Data contains only metadata.

This change adds the human-readable tool output as Data["content"] for wiki_search and wiki_read_page before the existing MCP conversion. It intentionally leaves the shared converter and other tools unchanged, avoiding a payload change for search_knowledge/read_document.

Type of Change

• 🐛 Bug fix
• ✨ New feature
• 💥 Breaking change
• 📚 Documentation update
• 🎨 Refactor
• ⚡ Performance improvement
• 🧪 Test
• 🔧 Configuration / Build / CI

Related Issue

Fixes #3575

Testing

• go test ./internal/mcpserver -count=1
• go vet ./internal/mcpserver
• golangci-lint run --new-from-rev=origin/main ./internal/mcpserver
• gofmt -l internal/mcpserver/tools_wiki.go internal/mcpserver/tools_wiki_test.go
• git diff --check

The focused test covers existing metadata preservation, nil structured data, existing content preservation, unsuccessful/empty results, the in-memory MCP result, and its JSON wire representation.

The full-repository lint/test gate was not claimed because this Windows environment lacks the repository's required native prerequisites: full lint type-checking cannot find sqlite3.h, and internal/agent/tools cannot link the prebuilt DuckDB C++ archive with the available MinGW runtime. These failures are outside the changed package; the focused package checks pass.

Checklist

• git diff --check origin/main...HEAD passes
• Changed source files are formatted
• Targeted tests for the changed packages/components pass
• Diff-scoped lint passes where applicable
• Full-repository checks were run, or unrelated/environment-dependent failures are documented above
• Self-reviewed the code
• Added/updated tests covering the change
• Updated related documentation (not needed; no public API docs changed)
• Breaking changes are clearly called out (none)

Screenshots / Recordings

Not applicable; this is an MCP response compatibility fix with no UI change.