chore(cli): migrate @fern-api/configuration-loader to use CliError

[FedeZara]

Description

Migrates @fern-api/configuration-loader to use explicit CliError error codes on every failAndThrow / failWithoutThrowing call site.

This is one of the package migration PRs that follow the error classification system introduced in #14749.

Changes Made

Assigned typed error codes across call sites in packages/cli/configuration-loader/src/.

Error codes used

Code	Usage
CONFIG_ERROR	Invalid generator configuration, missing required fields, unknown generator names
PARSE_ERROR	Malformed YAML/JSON configuration files, schema validation failures
VALIDATION_ERROR	Invalid color values, docs configuration validation

Files touched (grouped by area)

• Generators config: generators-yml/loadGeneratorsConfiguration.ts, addGenerator.ts, updateGeneratorGroup.ts, getGeneratorName.ts
• Schema validation: commons/validateSchema.ts
• Docs config: docs-yml/convertColorsConfiguration.ts, parseDocsConfiguration.ts
• Dependencies: dependencies-yml/convertDependenciesConfiguration.ts

Testing

• Existing tests pass (pnpm test, excluding e2e and pre-existing environment failures)

[FedeZara]

• chore(cli): migrate @fern-api/configuration-loader to use CliError #14993 👈 (View in Graphite)
• main

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