feat(jsonl): add omitempty to reduce JSONL bloat (beads-399)

Add omitempty JSON tags to Issue struct fields (Description, Status,
Priority, IssueType) and SetDefaults method to apply proper defaults
when importing JSONL with omitted fields.

This reduces JSONL file size for minimal issues like notifications
by not exporting empty/default values.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/autoflush.go

@@ -165,6 +165,7 @@ func autoImportIfNewer() {
 			fmt.Fprintf(os.Stderr, "Auto-import skipped: parse error at line %d: %v\nSnippet: %s\n", lineNo, err, snippet)
 			return
 		}
+		issue.SetDefaults() // Apply defaults for omitted fields (beads-399)
 
 		// Fix closed_at invariant: closed issues must have closed_at timestamp
 		if issue.Status == types.StatusClosed && issue.ClosedAt == nil {
@@ -662,6 +663,7 @@ func flushToJSONLWithState(state flushState) {
 				}
 				var issue types.Issue
 				if err := json.Unmarshal([]byte(line), &issue); err == nil {
+					issue.SetDefaults() // Apply defaults for omitted fields (beads-399)
 					issueMap[issue.ID] = &issue
 				} else {
 					// Warn about malformed JSONL lines

cmd/bd/autoimport.go

@@ -294,6 +294,7 @@ func importFromGit(ctx context.Context, dbFilePath string, store storage.Storage
 		if err := json.Unmarshal([]byte(line), &issue); err != nil {
 			return fmt.Errorf("failed to parse issue: %w", err)
 		}
+		issue.SetDefaults() // Apply defaults for omitted fields (beads-399)
 		issues = append(issues, &issue)
 	}
 

cmd/bd/compact.go

@@ -953,6 +953,7 @@ func pruneExpiredTombstones(customTTL time.Duration) (*TombstonePruneResult, err
 			// Skip corrupt lines
 			continue
 		}
+		issue.SetDefaults() // Apply defaults for omitted fields (beads-399)
 		allIssues = append(allIssues, &issue)
 	}
 	if err := file.Close(); err != nil {
@@ -1049,6 +1050,7 @@ func previewPruneTombstones(customTTL time.Duration) (*TombstonePruneResult, err
 			// Skip corrupt lines
 			continue
 		}
+		issue.SetDefaults() // Apply defaults for omitted fields (beads-399)
 		allIssues = append(allIssues, &issue)
 	}
 

cmd/bd/daemon_sync.go

@@ -183,6 +183,7 @@ func importToJSONLWithStore(ctx context.Context, store storage.Storage, jsonlPat
 			fmt.Fprintf(os.Stderr, "Warning: failed to parse JSONL line %d: %v\n", lineNum, err)
 			continue
 		}
+		issue.SetDefaults() // Apply defaults for omitted fields (beads-399)
 
 		issues = append(issues, &issue)
 	}

cmd/bd/import.go

@@ -205,6 +205,7 @@ NOTE: Import requires direct database access and does not work with daemon mode.
 				fmt.Fprintf(os.Stderr, "Error parsing line %d: %v\n", lineNum, err)
 				os.Exit(1)
 			}
+			issue.SetDefaults() // Apply defaults for omitted fields (beads-399)
 
 			allIssues = append(allIssues, &issue)
 		}

cmd/bd/nodb.go

@@ -103,6 +103,7 @@ func loadIssuesFromJSONL(path string) ([]*types.Issue, error) {
 		if err := json.Unmarshal([]byte(line), &issue); err != nil {
 			return nil, fmt.Errorf("line %d: %w", lineNum, err)
 		}
+		issue.SetDefaults() // Apply defaults for omitted fields (beads-399)
 
 		issues = append(issues, &issue)
 	}