policy+tui: raise coverage above target (M1)

policy 66% -> 94.7%: TestLoad exercises the previously-untested Load path —
empty/missing path fall back to Default, valid YAML parses onto the Default base
(absent fields keep their default; overrides apply), malformed YAML and a
non-regular file (directory) both error. Documents that a map override entry is
replaced wholesale by yaml.v3 (Evaluate re-merges defaults, so it's harmless).

tui 57% -> 87.8%: cover Init, the "o" open branches (URL vs none), "s" skip and
prev/next boundary guards, non-key messages, enter-at-last-item, esc/ctrl+c
quit, openURL's command, and Run's headless empty-list path. The residual is the
TTY-only tea.Program.Run() launch, not unit-testable headless.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/policy/policy_test.go

@@ -1,6 +1,8 @@
 package policy
 
 import (
+	"os"
+	"path/filepath"
 	"testing"
 	"time"
 
@@ -9,6 +11,50 @@ import (
 	"incredigo/internal/discover"
 )
 
+func TestLoad(t *testing.T) {
+	// Empty path → built-in default.
+	if p, err := Load(""); err != nil || p.Defaults.WarnAfter != 60 {
+		t.Fatalf("Load(\"\") = %+v, %v; want default", p, err)
+	}
+
+	// Missing file → default (not an error).
+	miss := filepath.Join(t.TempDir(), "nope.yaml")
+	if p, err := Load(miss); err != nil || p.Defaults.StaleAfter != 90 {
+		t.Fatalf("Load(missing) = %+v, %v; want default", p, err)
+	}
+
+	// Valid file → parsed onto the Default() base: a struct field absent from the
+	// file keeps its default (stale_after stays 90), while an override is applied.
+	f := filepath.Join(t.TempDir(), "policy.yaml")
+	if err := os.WriteFile(f, []byte("defaults:\n  warn_after: 10d\noverrides:\n  aws_key:\n    warn_after: 5d\n    stale_after: 45d\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	p, err := Load(f)
+	if err != nil {
+		t.Fatalf("Load(valid): %v", err)
+	}
+	if p.Defaults.WarnAfter != 10 || p.Defaults.StaleAfter != 90 {
+		t.Errorf("defaults = %+v, want {10 90} (stale kept from Default)", p.Defaults)
+	}
+	if got := p.Overrides[discover.KindAWSKey]; got.WarnAfter != 5 || got.StaleAfter != 45 {
+		t.Errorf("aws_key override = %+v, want {5 45}", got)
+	}
+
+	// Malformed YAML → error.
+	bad := filepath.Join(t.TempDir(), "bad.yaml")
+	if err := os.WriteFile(bad, []byte("defaults: [this is not a mapping"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := Load(bad); err == nil {
+		t.Error("Load(malformed) returned no error")
+	}
+
+	// Unreadable (a directory, not a regular file) → a non-IsNotExist error.
+	if _, err := Load(t.TempDir()); err == nil {
+		t.Error("Load(directory) returned no error")
+	}
+}
+
 func TestDaysUnmarshal(t *testing.T) {
 	ok := map[string]Days{
 		"60":     60,