fix: honor state root across telegram runtime

[grb02752-cmyk]

Summary

• route remaining cokacdir stateful Telegram/runtime paths through the configured state-root instead of hard-coded home paths
• move schedule and schedule-history handling onto the state-rooted path family
• ensure schedule result writes create their target directory before emitting .result files
• keep the macOS sensitive-target regression green while finishing the state-root wave

Files

• src/config.rs
• src/main.rs
• src/services/telegram.rs
• src/services/file_ops.rs

Verification

• cargo build
• cargo test test_state_root_dir_prefers_env_override -- --test-threads=1
• cargo test test_ensure_config_exists_uses_env_override -- --test-threads=1
• cargo test state_root_leak_tests -- --test-threads=1
• cargo test test_target_is_sensitive_private_prefix -- --test-threads=1
• isolated CLI smoke for --currenttime, --sendfile, and --cron register/list/remove under COKACDIR_STATE_ROOT=<tmp>

Notes

• this was verified in isolated checkouts only; no live rollout, service restart, or real ~/.cokacdir mutation was performed during prep

[grb02752-cmyk]

Verified in isolated checkouts only; no live rollout or service restart was performed.

Verification completed:

• cargo build
• cargo test test_state_root_dir_prefers_env_override -- --test-threads=1
• cargo test test_ensure_config_exists_uses_env_override -- --test-threads=1
• cargo test state_root_leak_tests -- --test-threads=1
• cargo test test_target_is_sensitive_private_prefix -- --test-threads=1
• isolated CLI smoke for --currenttime, --sendfile, and --cron register/list/remove under COKACDIR_STATE_ROOT=<tmp>

Result: ready from the patch-prep side; remaining action is maintainer merge / rollout choice.