feat(scoring): transition workflow learning and fix history UX (#39)

- add transition scoring engine to learn sequential workflows per
directory using command skeletons
- prioritize current active git branch over older branches in
suggestions
- restore strict chronological order for history navigation and bypass
AI re-ranking
- add in-memory session history for instant access to just-run commands
- fix PTY prompt not syncing when using arrow keys in the history menu
- fix history tie-breaker to properly prioritize newer commands by
assigning larger IDs
- fix potential mutex deadlock between bufferMu and pty write during
history navigation
- fix workspace git detection to remove depth limits and correctly
identify repositories with detached HEADs
- fix SQLite connection leaks in frecency queries
- fix global state leaks in history tests by snapshotting and restoring
registry states
- modernize string prefix checks using strings.CutPrefix

internal/workspace/workspace_test.go

@@ -4,6 +4,7 @@ import (
 	"os"
 	"path/filepath"
 	"testing"
+	"time"
 )
 
 func TestDetect_GitAndGoProject(t *testing.T) {
@@ -115,3 +116,38 @@ func TestDetect_MultiEcosystems(t *testing.T) {
 		t.Error("expected HasK8s to be true")
 	}
 }
+
+func TestDetectCached_BranchSwitchWithoutDirChange(t *testing.T) {
+	tmp := t.TempDir()
+	gitDir := filepath.Join(tmp, ".git")
+	_ = os.Mkdir(gitDir, 0755)
+
+	headPath := filepath.Join(gitDir, "HEAD")
+	_ = os.WriteFile(headPath, []byte("ref: refs/heads/main\n"), 0644)
+
+	dirInfoBefore, _ := os.Stat(tmp)
+
+	info1 := DetectCached(tmp)
+	if info1.GitBranch != "main" {
+		t.Fatalf("expected branch 'main', got %q", info1.GitBranch)
+	}
+
+	// Simulate branch switch by updating .git/HEAD only
+	// (this does not update the modtime of tmp on typical filesystems since tmp's direct children didn't change)
+	_ = os.WriteFile(headPath, []byte("ref: refs/heads/feature\n"), 0644)
+	
+	// Force the modtime of HEAD to be distinct to avoid flakiness on low-res file systems
+	infoAfter, _ := os.Stat(headPath)
+	newMod := infoAfter.ModTime().Add(2 * time.Second)
+	_ = os.Chtimes(headPath, newMod, newMod)
+
+	dirInfoAfter, _ := os.Stat(tmp)
+	if dirInfoBefore.ModTime() != dirInfoAfter.ModTime() {
+		t.Log("Note: directory modtime changed automatically on this filesystem")
+	}
+
+	info2 := DetectCached(tmp)
+	if info2.GitBranch != "feature" {
+		t.Fatalf("expected branch 'feature', got %q", info2.GitBranch)
+	}
+}