Serve a tools bundle as soon as it is in place, changed or gone, with no restart; say why a bundle cannot start (issue 1945)

node-tools loaded every bundle once at start, so a bundle delivered after
it started (mesh-files on shanks, 2026-10-25 12:08) went unserved until a
hand restart, and a missing file was said as "not executable". The
runtime now watches the entrypoints' directories with inotify, loads a
module again once a burst of changes settles, and discovery answers with
what is served now. A bundle that cannot start says it does not exist, is
not executable with its mode, or the exec error.

Tests: 1945/AC19-AC22 in internal/runtime/reload_test.go.

node-tools/internal/runtime/provision.go

@@ -198,6 +198,18 @@ func (p *provisionWatches) told(module string, changed bus.ProvisionChanged) []*
 	return out
 }
 
+// stopModule stops every watch of one module, whose bundle is loaded again.
+func (p *provisionWatches) stopModule(module string) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	for w := range p.of[module] {
+		w.mu.Lock()
+		w.stopped = true
+		w.mu.Unlock()
+	}
+	delete(p.of, module)
+}
+
 func (p *provisionWatches) stopAll() {
 	p.mu.Lock()
 	defer p.mu.Unlock()