docs(tooling): tell consumers' agents how to code with Crafter.Debug

The consumer notes only said how to drive a running app. They now also
say how to add to what an agent can reach: where the hook points and
registrations go, gating pause and step, registering commands,
watches, samples and checks, and the rules that keep that code right
(handlers run on the app's thread and must not block; Async for
results that take frames; call the app's own code paths instead of
re-implementing them, the lesson from 3DForts' drifting verbs; Group
for per-object state; which types travel).

All of it stays in tooling/AGENTS.consumer.md, which every build
merges through the unconditional pragma. Notes beside the root
project.cpp would only come with debug builds, when the library is in
the graph, and would then duplicate these; AGENTS.template.md now says
so.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

AGENTS.template.md

@@ -17,6 +17,10 @@ The client is one of the library's dependencies only so that a consumer's debug
 
 `tooling/` is a separate project, `Crafter.Debug.Build`. Consumers load it with `#pragma crafter dependency ... project "tooling/project.cpp"`. Its `Debug::Use` adds the library under the consumer's flag and writes the consumer's `build/crafter-debug` launcher at load time.
 
+`tooling/AGENTS.consumer.md` is the only notes file consumers get, and it covers both driving the app and coding with it. Crafter.Build merges a dependency's notes only when that dependency is in the build:
+- **The tooling** comes in through the pragma, which is unconditional, so its notes are there after every build.
+- **The root library** comes in only under the consumer's debug flag. Notes beside the root `project.cpp` would vanish after plain builds and appear twice after debug builds, so the root has none.
+
 `examples/Basic` is a consumer that uses this checkout through a local pragma path.
 
 ## Dev environment