Sync MCP surface to SPEC §7 process model

Rename list_children/read_output/kill/send_message_to to their SPEC §7
process_id-shaped names; drop report_to_parent (direction inferred by
send_message) and policy_check (replaced by per-project trust gating).
Add the SPEC's missing tools: start_process, restart_process,
close_process, rename_process, select_process, get_process_status,
get_project_status, get_process_raw_output, search_output,
get_process_ports, whoami, help.

Process model now distinguishes agent/terminal/command kinds with
opaque p_<6hex> IDs. Command entries are session-persistent so they
survive PTY exit and can be Restart'd. Status enum gains starting and
stopped. screen_version, port detection, and bracketed-paste send_input
land alongside.

Trust gating (internal/trust) replaces the regex policy: command-preset
spawns return needs_trust on first use; the user confirms in a
status-line modal and the grant persists to
\$XDG_DATA_HOME/patterm/projects/<key>/trust.json.

Tests cover send_message direction inference (parent↔child, sibling
rejection, nil caller paths) and trust grant persistence across reopen.

internal/trust/trust_test.go

@@ -0,0 +1,61 @@
+package trust
+
+import (
+	"os"
+	"testing"
+)
+
+func TestStoreGrantPersists(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("XDG_DATA_HOME", dir)
+
+	s1, err := Open("projkey")
+	if err != nil {
+		t.Fatalf("open: %v", err)
+	}
+	if s1.IsTrusted("vitest") {
+		t.Fatalf("fresh store should not trust anything")
+	}
+	if err := s1.Grant("vitest"); err != nil {
+		t.Fatalf("grant: %v", err)
+	}
+	if !s1.IsTrusted("vitest") {
+		t.Fatalf("grant didn't take effect")
+	}
+
+	// Re-open and confirm persistence.
+	s2, err := Open("projkey")
+	if err != nil {
+		t.Fatalf("reopen: %v", err)
+	}
+	if !s2.IsTrusted("vitest") {
+		t.Fatalf("grant did not persist across reopen")
+	}
+	if s2.IsTrusted("bun-dev") {
+		t.Fatalf("unrelated preset should not be trusted")
+	}
+
+	// Verify the file exists at the expected path.
+	if _, err := os.Stat(s2.Path()); err != nil {
+		t.Fatalf("stat trust.json: %v", err)
+	}
+}
+
+func TestStoreRevokeWithoutGrantIsNoop(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("XDG_DATA_HOME", dir)
+
+	s, err := Open("projkey")
+	if err != nil {
+		t.Fatalf("open: %v", err)
+	}
+	if err := s.Revoke("never-granted"); err != nil {
+		t.Fatalf("revoke noop should succeed: %v", err)
+	}
+}
+
+func TestStoreOpenRequiresProjectKey(t *testing.T) {
+	if _, err := Open(""); err == nil {
+		t.Fatalf("open with empty project key should fail")
+	}
+}