Assign readable ticket keys from project code and sequence.

Replace UUID-looking sync labels in TUI and web with keys like TAS-1,
while keeping the remote UUID for task-master matching.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/sqlite/projectcode_test.go

@@ -0,0 +1,32 @@
+package sqlite
+
+import "testing"
+
+func TestDeriveProjectCode(t *testing.T) {
+	cases := []struct {
+		name, want string
+	}{
+		{"Alpha", "ALP"},
+		{"task-master", "TAS"},
+		{"AB", "ABX"},
+		{"12", "XXX"},
+		{"Büro Projekt", "BRO"}, // non-ASCII letters skipped
+		{"my project", "MYP"},
+	}
+	for _, tc := range cases {
+		if got := DeriveProjectCode(tc.name); got != tc.want {
+			t.Errorf("DeriveProjectCode(%q)=%q want %q", tc.name, got, tc.want)
+		}
+	}
+}
+
+func TestNextUniqueCode(t *testing.T) {
+	used := map[string]bool{"ALP": true, "ALA": true}
+	got := nextUniqueCode("Alpha", used)
+	if got == "ALP" || got == "ALA" {
+		t.Fatalf("expected unique code, got %q", got)
+	}
+	if len(got) != 3 {
+		t.Fatalf("len=%d code=%q", len(got), got)
+	}
+}