feat: v0.3.0a — add api command, pr diff/comment/review, structured errors

New commands:
- fgj api: raw REST API passthrough with field inference and path interpolation
- fgj pr diff: view PR diffs with color, --name-only, --stat
- fgj pr comment: add comments to pull requests
- fgj pr review: approve, request changes, or comment on PRs

Agentic enhancements:
- --json-errors flag for structured JSON error output on stderr
- APIError type wrapping HTTP status codes for machine consumption
- Error codes: auth_required, not_found, api_error, invalid_input, etc.

Docs updated for forgejo.zerova.net/sid/fgj-sid fork.

cmd/root.go

@@ -5,7 +5,7 @@ import (
 	"os"
 	"strings"
 
-	"codeberg.org/romaintb/fgj/internal/git"
+	"forgejo.zerova.net/sid/fgj-sid/internal/git"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 )
@@ -18,7 +18,7 @@ var rootCmd = &cobra.Command{
 	Short: "Forgejo CLI tool - work seamlessly with Forgejo from the command line",
 	Long: `fgj is a command line tool for Forgejo instances (including Codeberg).
 It brings pull requests, issues, and other Forgejo concepts to the terminal.`,
-	Version:       "0.2.0",
+	Version:       "0.3.0a",
 	SilenceErrors: true,
 }