Support copying ignored secrets.auto.tfvars into worktrees

[nettee]

Summary

• add a global recursive ignored file config for worktree initialization
• copy ignored secrets.auto.tfvars files from the repo root and all nested directories when creating or initializing worktrees
• keep copy reporting and snapshot replay aligned with the shared config, and extend e2e coverage for tfvars copy and non-matching filenames

Why

• issue 支持在创建 worktree 时复制所有子目录下的 secrets.auto.tfvars 文件，并抽象为全局配置 #76 requests parity with the existing .env behavior for secrets.auto.tfvars
• the previous implementation hard-coded .env handling in multiple places, which made adding another recursive file type invasive

Validation

• cargo test
• uv run --project e2e pytest e2e/test_env_copy.py -q

Closes #76

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