brokerd: recall and memory, decided under built-in grants

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

crates/brokerd/src/policy/matching.rs

@@ -37,7 +37,7 @@ pub(super) fn match_grants(
     let mut expired = false;
     let mut tainted = false;
 
-    for loaded in grants.grants() {
+    for loaded in grants.matchable() {
         // M1: only grants for this tool play a part.
         if loaded.grant.tool != args.tool().as_str() {
             continue;
@@ -93,6 +93,8 @@ fn covers(args: &ToolArgs, grant: &Grant) -> Option<Option<String>> {
             }
         }
         ToolArgs::Shell { cwd: Some(cwd), .. } => best_path(grant, cwd, true),
+        // The memory tools take no constraints: their grants are built in (M5a spec, section 8).
+        ToolArgs::Recall(_) | ToolArgs::Memory(_) => Some(None),
         ToolArgs::HttpFetch(target) => {
             if grant
                 .constraints