Fix critical P0 database reinitialization bug (bd-130)

Fixes silent data loss when .beads/ directory removed and daemon auto-starts.

Root cause: checkGitForIssues() hardcoded 'issues.jsonl' but git tracks 'beads.jsonl'

Changes:
- Fix A (bd-131): checkGitForIssues() tries beads.jsonl first, then issues.jsonl
- Fix B (bd-132): Immediate export after import in bd init to prevent daemon race
- Fix C (bd-133): Safety check that fails loudly if import fails
- Fix D (bd-134): Daemon startup auto-import when DB empty but git has issues
- Tests (bd-135): Comprehensive integration test suite

Oracle-recommended improvements:
- Export to exact git-relative path (prevents path drift)
- filepath.ToSlash for Windows git compatibility
- 64MB scanner buffer for large JSONL lines
- Improved safety check messages (only suggest local file if exists)

All tests passing. No regressions.

Amp-Thread-ID: https://ampcode.com/threads/T-0e31dc6a-a0d9-46c6-87b2-cfdebe829a52
Co-authored-by: Amp <amp@ampcode.com>

cmd/bd/init.go

@@ -145,11 +145,56 @@ bd.db
 		fmt.Fprintf(os.Stderr, "Try manually: git show HEAD:%s | bd import -i /dev/stdin\n", jsonlPath)
 		}
 		// Non-fatal - continue with empty database
-		} else if !quiet {
-		fmt.Fprintf(os.Stderr, "✓ Successfully imported %d issues from git.\n\n", issueCount)
+		} else {
+		// CRITICAL: Immediately export to local JSONL to prevent daemon race condition
+		// The daemon might auto-start before the 5-second auto-flush debounce completes
+		// Write to exact git-relative path to prevent path drift
+		gitRoot := findGitRoot()
+		if gitRoot == "" {
+		if !quiet {
+		 fmt.Fprintf(os.Stderr, "Warning: could not find git root for export\n")
+		 }
+		} else {
+		absJSONL := filepath.Join(gitRoot, filepath.FromSlash(jsonlPath))
+		 if err := os.MkdirAll(filepath.Dir(absJSONL), 0750); err != nil {
+		   if !quiet {
+					fmt.Fprintf(os.Stderr, "Warning: failed to create export dir: %v\n", err)
+				}
+			} else if err := exportToJSONLWithStore(ctx, store, absJSONL); err != nil {
+				if !quiet {
+					fmt.Fprintf(os.Stderr, "Warning: failed to export after import: %v\n", err)
+				}
+			}
 		}
+		if !quiet {
+			fmt.Fprintf(os.Stderr, "✓ Successfully imported %d issues from git.\n\n", issueCount)
+		}
+	}
 }
 
+	// Safety check: verify import succeeded and catch silent data loss
+	stats, err := store.GetStatistics(ctx)
+	if err == nil && stats.TotalIssues == 0 {
+		// DB empty after init - check if git has issues we failed to import
+		recheck, recheckPath := checkGitForIssues()
+		if recheck > 0 {
+			fmt.Fprintf(os.Stderr, "\n❌ ERROR: Database empty but git has %d issues!\n", recheck)
+			fmt.Fprintf(os.Stderr, "Auto-import failed. Manual recovery:\n")
+			fmt.Fprintf(os.Stderr, "  git show HEAD:%s | bd import -i /dev/stdin\n", filepath.ToSlash(recheckPath))
+			// Only suggest local file import if file exists
+			gitRoot := findGitRoot()
+			if gitRoot != "" {
+				localFile := filepath.Join(gitRoot, filepath.FromSlash(recheckPath))
+				if _, err := os.Stat(localFile); err == nil {
+					fmt.Fprintf(os.Stderr, "Or:\n")
+					fmt.Fprintf(os.Stderr, "  bd import -i %s\n", localFile)
+				}
+			}
+			_ = store.Close()
+			os.Exit(1)
+		}
+	}
+
 if err := store.Close(); err != nil {
 		fmt.Fprintf(os.Stderr, "Warning: failed to close database: %v\n", err)
 }