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>

SKILL.md

@@ -79,6 +79,12 @@ kb jobs --status failed --format json    # filter by status
 kb jobs <job_id> --format json           # job details
 ```
 
+## Examples
+
+```bash
+kb examples                              # show common usage examples
+```
+
 ## Engine status and maintenance
 
 ```bash
@@ -102,18 +108,14 @@ All commands support:
     {
       "chunk_id": 1423,
       "score": 0.031,
-      "score_breakdown": {"fts": 0.016, "vector": 0.015},
       "text": "To install the latest version of git from source...",
-      "source": {
-        "document_id": 42,
-        "title": "Git Admin Guide",
-        "path": "/home/user/docs/git-admin.pdf",
-        "type": "pdf",
-        "page": 12,
-        "chunk_index": 3,
-        "total_chunks": 28,
-        "tags": ["git", "admin"]
-      }
+      "chunk_index": 3,
+      "chunk_metadata": {"page": 12},
+      "title": "Git Admin Guide",
+      "doc_type": "pdf",
+      "source_path": "/home/user/docs/git-admin.pdf",
+      "created_at": "2026-03-15T10:30:00",
+      "tags": ["git", "admin"]
     }
   ],
   "total_matches": 47,
@@ -160,7 +162,7 @@ Use filters when the question implies a specific domain:
 
 - Always use `--format json` for machine parsing
 - The `score` field is relative, not absolute — compare scores within a result set
-- `source.page` is only present for PDF documents
-- `source.section_header` is only present for markdown documents with headers
+- `chunk_metadata.page` is only present for PDF documents
+- `chunk_metadata.section_header` is only present for markdown documents with headers
 - Results are already ranked by relevance (hybrid FTS + vector search)
 - Duplicate files are detected at upload time (HTTP 409) — the client handles this gracefully