Make lib consistent with cli format

[creatorrr]

• Each template name should be in kebab case abc-def #2
• Rename julep.toml to julep.yaml #3
• Adapt julep.yaml to the new schema #4
• Move other files in the template inside <template>/src #5

Schema for julep.yaml

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "https://example.com/julep.schema.json",
  "title": "Julep Project Configuration Schema",
  "type": "object",
  "properties": {
    "agents": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "definition": {
            "type": "string",
            "description": "Path to the file defining the agent."
          },
          "canonical_name": {
            "type": "string",
            "description": "A unique reference name for the agent."
          }
        },
        "required": ["definition"],
        "additionalProperties": false
      }
    },
    "tasks": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "agent_id": {
            "type": "string",
            "description": "Reference to an agent ID or a templated expression (e.g. {agents[0].id})."
          },
          "definition": {
            "type": "string",
            "description": "Path to the file defining the task workflow."
          }
        },
        "required": ["agent_id", "definition"],
        "additionalProperties": false
      }
    },
    "tools": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "agent_id": {
            "type": "string",
            "description": "Reference to an agent ID or a templated expression (e.g. {agents['awesome-agent'].id})."
          },
          "definition": {
            "type": "string",
            "description": "Path to the tool configuration or definition file."
          }
        },
        "required": ["agent_id", "definition"],
        "additionalProperties": false
      }
    }
  },
  "additionalProperties": false
}