chore: rename packages/ to crates/

Move all 29 workspace members from packages/<name>/ to crates/<name>/.
Updates: workspace Cargo.toml (members + path deps), justfile, root
CLAUDE.md, scripts/build/CARGO_INSTALL.md, docs/architecture/crates.md
(renamed from packages.md), structural references in docs/architecture
and docs/configuration, per-crate CLAUDE.md self-references. Historical
plans, reports, and building/ docs are left untouched.

No behavior change; just check-all stays green and fermata tests pass.

tests/core_op_decision.rs

@@ -0,0 +1,42 @@
+use dirigent_fermata::core::{Decision, Op, Reason, Rule};
+
+#[test]
+fn op_variants_exist() {
+    let _ = Op::Read;
+    let _ = Op::Write;
+    let _ = Op::Execute;
+}
+
+#[test]
+fn decision_allow_is_simple() {
+    let d = Decision::Allow;
+    assert!(matches!(d, Decision::Allow));
+}
+
+#[test]
+fn decision_deny_carries_reason() {
+    let rule = Rule {
+        source: "/proj/.botignore".into(),
+        pattern: ".env".into(),
+    };
+    let d = Decision::Deny(Reason {
+        message: "blocked by .botignore".into(),
+        rule: Some(rule),
+    });
+    match d {
+        Decision::Deny(r) => {
+            assert_eq!(r.message, "blocked by .botignore");
+            assert!(r.rule.is_some());
+        }
+        _ => panic!("expected Deny"),
+    }
+}
+
+#[test]
+fn decision_ask_carries_reason() {
+    let d = Decision::Ask(Reason {
+        message: "needs confirmation".into(),
+        rule: None,
+    });
+    assert!(matches!(d, Decision::Ask(_)));
+}