Implement Schema-Aware config set/get CLI Commands

## Overview

Implement `config set` and `config get` CLI commands for reading and updating etcd config values with schema validation.

## Requirements

### config get

- Get specific config field value from etcd
- Show field type and description from schema
- Support dot notation for nested fields (e.g., database.host)

### config set

- Set config field value in etcd
- Validate value against schema before setting
- Support type coercion based on schema (string to int, etc.)
- Prevent setting invalid values

## Schema Validation

- Validate field exists in schema
- Validate value type matches schema
- Validate value constraints (min/max, pattern, enum values)
- Show helpful error messages on validation failure

## Acceptance Criteria

- [ ] `config get` retrieves values from etcd
- [ ] `config set` validates against schema before writing
- [ ] Type coercion based on schema field type
- [ ] Clear error messages for invalid values
- [ ] Supports nested field paths (dot notation)
- [ ] Works for all components

JIRA Issue: BA-3477

Start by locating the existing CLI command entry points, configuration schema handling, and etcd read/write integration; the issue does not name specific files or tests. Trace how configuration is represented across components and run the existing CLI test suite if available. Done means both commands support nested fields, schema validation, type coercion, and clear errors for invalid values.

Written by the indexing model from the issue text.