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

integration/history_test.go

@@ -0,0 +1,52 @@
+package integration
+
+import (
+	"testing"
+)
+
+func TestRecordSessionCommand_MergeAndDeduplicate(t *testing.T) {
+	sessionHistoryMu.Lock()
+	origSessionHistory := sessionHistory
+	sessionHistory = nil
+	sessionHistoryMu.Unlock()
+
+	mu.Lock()
+	origHistoryCache := historyCache
+	historyCache = nil
+	mu.Unlock()
+
+	t.Cleanup(func() {
+		sessionHistoryMu.Lock()
+		sessionHistory = origSessionHistory
+		sessionHistoryMu.Unlock()
+
+		mu.Lock()
+		historyCache = origHistoryCache
+		mu.Unlock()
+	})
+
+	RecordSessionCommand("git status")
+	RecordSessionCommand("npm run dev")
+	RecordSessionCommand("npm run dev") // duplicate subsequent command should be ignored
+	RecordSessionCommand("git push origin fix/scoring")
+
+	results, err := SearchHistory("", nil)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if len(results) < 3 {
+		t.Fatalf("expected at least 3 session commands in search results, got %d", len(results))
+	}
+
+	// newest session command must be results[0]
+	if results[0].Cmd != "git push origin fix/scoring" {
+		t.Errorf("expected results[0] to be 'git push origin fix/scoring', got %q", results[0].Cmd)
+	}
+	if results[1].Cmd != "npm run dev" {
+		t.Errorf("expected results[1] to be 'npm run dev', got %q", results[1].Cmd)
+	}
+	if results[2].Cmd != "git status" {
+		t.Errorf("expected results[2] to be 'git status', got %q", results[2].Cmd)
+	}
+}