Fix search human-mode output to match engine API response

The Go client struct expected a nested document object and top-level
page/section fields, but the engine returns flat results with metadata
in chunk_metadata. This caused empty display for title, type, tags,
page, and section in human output mode.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

openspec/changes/archive/2026-04-02-fix-search-human-output/proposal.md

@@ -0,0 +1,24 @@
+## Why
+
+The Go client's human-mode search output struct expects a nested `document` object and top-level `page`/`section` fields, but the engine API returns flat results with `title`, `doc_type`, `tags` at the result level and `page`/`section_header` inside `chunk_metadata`. This means human-mode display shows empty values for title, type, tags, page, and section.
+
+## What Changes
+
+- Fix the Go client search result struct to match the flat engine API response format
+- Extract `page` and `section_header` from the `chunk_metadata` map instead of expecting them as top-level fields
+- Human-mode output will correctly display document title, type, tags, page number, and section header
+
+## Capabilities
+
+### New Capabilities
+
+(none)
+
+### Modified Capabilities
+
+- `go-client`: Fix search result parsing to match actual engine API response shape
+
+## Impact
+
+- `client/cmd/search.go` — struct definition and display logic
+- No API changes, no breaking changes — this is a bug fix aligning the client with the existing API contract