Add E2E shell tests with SLAS auto-tenant creation and job body support

[clavery]

Summary

These tests are e2e using a single shell script to demonstrate a real world use case (this also serves as documentation) of "easy setup" while providing a secondary E2E regression testing workflow.

As part of running this this PR fixes a bunch of big and small issues with the commands and improves the DX.

• Add comprehensive E2E shell test suite that exercises the full CLI workflow
• Add --body flag to job run for system jobs with non-standard request schemas
• Add automatic SLAS tenant creation when creating clients (with --[no-]create-tenant flag)
• Fix various issues with JSON output, structured logging, and config handling

Changes

E2E Shell Tests

• New e2e_cli_test.sh script that tests: sandbox creation, code deployment, site import, search indexing, SLAS client management, and shopper API access
• GitHub Actions workflow (e2e-shell-tests.yml) that runs daily at 3 AM UTC
• Test fixtures for site archive import (catalog, inventory, pricebook, site preferences)

Job Run Command

• Add --body/-B flag for raw JSON request body (mutually exclusive with -P)
• Enables running system jobs like sfcc-search-index-product-full-update that use non-standard schemas

SLAS Client Create Command

• Automatically create SLAS tenant if it doesn't exist (enabled by default)
• Add --[no-]create-tenant flag to control this behavior
• Handle SLAS API returning 400 with TenantNotFoundException instead of 404

Bug Fixes

• Fix JSON error output to go to stderr when --json flag is used
• Add structured logging with context fields in ODS create command
• Add hostname mismatch detection to ignore dw.json when explicit server differs
• Add 2-second delay before first sandbox poll to avoid 404 errors

Documentation

• Update job commands documentation with --body flag and system job examples
• Update SLAS documentation with --create-tenant flag
• Update CLI skills for job and SLAS topics

Test plan

• Run E2E shell tests locally with valid credentials
• Verify b2c job run sfcc-search-index-product-full-update --body '{"site_scope":["RefArch"]}' works
• Verify b2c slas client create auto-creates tenant on new instances
• Verify --no-create-tenant skips tenant creation
• Verify JSON errors go to stderr with --json flag