search: Pfad und Titel vollstaendig in der Trefferzeile, Trunkierung wird benannt (schliesst #100)

Files changed:
- AGENTS.md
- CHANGES.md
- VERSION
- instructions/wiki-query/SKILL.md
- tools/CONTRACT.md
- tools/chemenu/api.py
- tools/chemenu/commands/search.py
- tools/chemenu/mcp/server.py
- tools/chemenu/search/service.py
- tools/chemenu/search/types.py
- tools/chemenu/tests/test_api.py
- tools/chemenu/tests/test_mcp_server.py
- tools/chemenu/tests/test_search.py

AGENTS.md

@@ -251,6 +251,13 @@ tools/wikitool search --field entity_type=system --field '!sources'
 
 `search` is read-only and exempt from the iteration budget.
 
+**It is also exhaustive, so do not grep `kb/` yourself.** `search` *is* a `rg` run over `kb/`,
+enriched with each hit's frontmatter and ranked; a grep of your own can therefore surface no
+page it missed, only the generated files it deliberately excludes - `kb/index.md`, `kb/log.md`,
+`kb/provenance.md`, every `INDEX.md` - which invariant 1 forbids acting on anyway. Each hit
+carries the page's full path and full title, so it can be opened and passed to the commands
+that take a title. A result cut short by `--limit` says so and names the total.
+
 ## Gates
 
 Four limits are enforced in code rather than by instruction, because a prompt-level limit is