Learn/crawl/nitin ex1 orientation

[sanghinitin]

Error fix using GHCP learning

Description

Enhanced EcErrorHandler with transient error classification, error counting, consistent exit-status enforcement, and expanded rescue clauses in backup/restore/import commands.

Changes:

• Added TRANSIENT_ERRORS constant to classify network/server errors (ECONNRESET, ECONNREFUSED, ETIMEDOUT, EHOSTUNREACH)
• Added error_count tracking and has_errors? predicate
• Added transient_error?(ex) method to tag errors as transient vs permanent in error logs
• at_exit hook now enforces exit 1 when errors occurred (even with -VVV flag)
• Added suppress_exit: option for testability
• Expanded rescue clauses in ec_backup.rb, ec_restore.rb, ec_import.rb to catch Net::HTTPFatalError and Errno::ECONNRESET/ECONNREFUSED/ETIMEDOUT
• Added require 'digest' guard in ec_base.rb for Ruby >= 3.2 compatibility
• 22 RSpec examples covering all new behavior

AI Track: Walk / Exercise 1 (Repo Orientation + Low-Risk Module)

Related Issue

GHCP Learning Track – Crawl/Walk exercise 1: repo orientation and low-risk module improvement.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (non-breaking change that does not add functionality or fix an issue)

Checklist:

• I have read the CONTRIBUTING document.
• I have run the pre-merge tests locally and they pass.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• If Gemfile.lock has changed, I have used --conservative to do it and included the full output in the Description above.
• All new and existing tests passed.
• All commits have been signed-off for the Developer Certificate of Origin.