Better enable go extensions (#14)

* deps: run go mod tidy

* beads: Add public Go API for bd extensions

Implements a minimal public API to enable Go-based extensions without
exposing internal packages:

**New beads.go package:**
- Exports essential types: Issue, Status, IssueType, WorkFilter
- Provides status and issue type constants
- Exposes NewSQLiteStorage() as main entry point for extensions
- Includes comprehensive package documentation

**Updated EXTENDING.md:**
- Replaced internal package imports with public beads package
- Updated function calls to use new public API
- Changed sqlite.New() to beads.NewSQLiteStorage()
- Updated GetReady() to GetReadyWork() with WorkFilter

This enables clean Go-based orchestration extensions while maintaining
API stability and hiding internal implementation details.

* beads: Refine Go extensions API and documentation

Updates to the public Go API implementation following initial commit:

- Enhanced beads.go with refined extension interface
- Updated EXTENDING.md with clearer documentation
- Modified cmd/bd/main.go to support extension loading

Continues work on enabling Go-based bd extensions.

* Fix EXTENDING.md to use beads.WorkFilter instead of types.WorkFilter

The public API exports WorkFilter as beads.WorkFilter, not types.WorkFilter.
This fixes the code example to match the imports shown.

---------

Co-authored-by: Steve Yegge <steve.yegge@gmail.com>

cmd/bd/main.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/fatih/color"
 	"github.com/spf13/cobra"
+	"github.com/steveyegge/beads"
 	"github.com/steveyegge/beads/internal/storage"
 	"github.com/steveyegge/beads/internal/storage/sqlite"
 	"github.com/steveyegge/beads/internal/types"
@@ -58,15 +59,11 @@ var rootCmd = &cobra.Command{
 
 		// Initialize storage
 		if dbPath == "" {
-			// Try to find database in order:
-			// 1. $BEADS_DB environment variable
-			// 2. .beads/*.db in current directory or ancestors
-			// 3. ~/.beads/default.db
-			if envDB := os.Getenv("BEADS_DB"); envDB != "" {
-				dbPath = envDB
-			} else if foundDB := findDatabase(); foundDB != "" {
+			// Use public API to find database (same logic as extensions)
+			if foundDB := beads.FindDatabasePath(); foundDB != "" {
 				dbPath = foundDB
 			} else {
+				// Fallback to default location (will be created by init command)
 				home, _ := os.UserHomeDir()
 				dbPath = filepath.Join(home, ".beads", "default.db")
 			}
@@ -128,37 +125,6 @@ var rootCmd = &cobra.Command{
 	},
 }
 
-// findDatabase searches for .beads/*.db in current directory and ancestors
-func findDatabase() string {
-	dir, err := os.Getwd()
-	if err != nil {
-		return ""
-	}
-
-	// Walk up directory tree looking for .beads/ directory
-	for {
-		beadsDir := filepath.Join(dir, ".beads")
-		if info, err := os.Stat(beadsDir); err == nil && info.IsDir() {
-			// Found .beads/ directory, look for *.db files
-			matches, err := filepath.Glob(filepath.Join(beadsDir, "*.db"))
-			if err == nil && len(matches) > 0 {
-				// Return first .db file found
-				return matches[0]
-			}
-		}
-
-		// Move up one directory
-		parent := filepath.Dir(dir)
-		if parent == dir {
-			// Reached filesystem root
-			break
-		}
-		dir = parent
-	}
-
-	return ""
-}
-
 // outputJSON outputs data as pretty-printed JSON
 func outputJSON(v interface{}) {
 	encoder := json.NewEncoder(os.Stdout)
@@ -171,26 +137,19 @@ func outputJSON(v interface{}) {
 
 // findJSONLPath finds the JSONL file path for the current database
 func findJSONLPath() string {
-	// Get the directory containing the database
-	dbDir := filepath.Dir(dbPath)
+	// Use public API for path discovery
+	jsonlPath := beads.FindJSONLPath(dbPath)
 
 	// Ensure the directory exists (important for new databases)
+	// This is the only difference from the public API - we create the directory
+	dbDir := filepath.Dir(dbPath)
 	if err := os.MkdirAll(dbDir, 0755); err != nil {
-		// If we can't create the directory, return default path anyway
+		// If we can't create the directory, return discovered path anyway
 		// (the subsequent write will fail with a clearer error)
-		return filepath.Join(dbDir, "issues.jsonl")
+		return jsonlPath
 	}
 
-	// Look for existing .jsonl files in the .beads directory
-	pattern := filepath.Join(dbDir, "*.jsonl")
-	matches, err := filepath.Glob(pattern)
-	if err == nil && len(matches) > 0 {
-		// Return the first .jsonl file found
-		return matches[0]
-	}
-
-	// Default to issues.jsonl
-	return filepath.Join(dbDir, "issues.jsonl")
+	return jsonlPath
 }
 
 // autoImportIfNewer checks if JSONL is newer than DB and imports if so