feat: expose ctx.task.name and ctx.task.group in TaskContext

[thesayyn]

Summary

• Adds a new TaskInfo Starlark type (engine/task_info.rs) with name: string and group: list[string] attributes
• Exposes it as ctx.task on both the mutable TaskContext and its frozen counterpart FrozenTaskContext
• Populates TaskInfo from ConfiguredTask.get_name() / get_group() at task execution time in both execute_task() and execute_task_with_args()
• Registers TaskInfo in the global type registry so it appears in Starlark type introspection

Usage

def impl(ctx: TaskContext):
    print(ctx.task.name)   # e.g. "deploy"
    print(ctx.task.group)  # e.g. ["dangerous", "release"]

my_task = task(
    name = "deploy",
    group = ["dangerous", "release"],
    implementation = impl,
)

Test plan

• cargo build -p axl-runtime compiles clean
• test_task_info added to .aspect/axl.axl asserts ctx.task.name == "axl" and ctx.task.group == ["tests"] against the live task declaration

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