Fix/import template fix: use sentinel error for resource not-found detection in import

[davhparry]

Description

Fixes ipctl import template --replace failing with "item with name '...' not found" when the template does not yet exist on the server. The root cause was fragile err.Error() string comparisons in runners that checked for resource-specific strings (e.g. "template not found"), while FindByName returned a generic "item with name '...' not found" string — the two never matched.

Type of Change

• [x ] Bug fix
• New feature
• Documentation
• Refactor
• Chore

Changes Made

Changes
pkg/resources/base.go — Added ErrNotFound sentinel and NotFoundError struct with an Is() method so errors.Is(err, ErrNotFound) works correctly
pkg/resources/FindByName — Added kind parameter so errors report the resource type (e.g. "template 'foo' not found")
pkg/resources/{accounts,device_groups,groups,jsonforms,models,projects,templates,workflows}.go — Updated all FindByName call sites to pass the resource kind
internal/runners/{templates,models,jsonforms}.go — Replaced err.Error() != "X not found" string checks with !errors.Is(err, resources.ErrNotFound)
pkg/resources/base_test.go — Unit tests for FindByName and ErrNotFound
internal/runners/templates_test.go — Integration tests covering the fixed import scenario

Testing

done
Unit tests (pkg/resources/base_test.go)
done
Integration tests (internal/runners/templates_test.go)
done
Full test suite passes (make test)
done
Manually verified import template

• Tested Importing a new template, with and without --replace flag - Import successful
• Tested Importing exiting template without --replace flag - Import error - already exist, use --replace flag
• Tested Importing a non-existent template - Error - file not found

Related Issues

Closes #196

Checklist

• [ x] Code follows the project's style guidelines
• [ x] Self-review of code has been performed
• [ x] Code has been commented where necessary
• [ x] Tested with make setup or relevant profile
• [ x] Commits follow conventional format (type: subject)
• [ x] No secrets or credentials committed
• [ x] Documentation has been updated accordingly
• [ x] PR has been labeled appropriately (enhancement, bug, documentation, refactor, chore)