Fix detect_deletions disable gating and harden timeout handling

[tomerh2001]

Summary

• Fix detect_deletions gating so disabled jobs do not start folder watchers (main.py now checks .enabled).
• Add JobParams.__bool__ so object truthiness consistently reflects job enabled state.
• Add configurable global HTTP timeout via general.request_timeout (and env REQUEST_TIMEOUT) instead of a hardcoded 15s timeout in make_request.
• Add runtime error boundaries so request failures in ARR/download-client job groups are logged and the main loop keeps running instead of crashing.
• Update docs/example config for request_timeout and add regression tests.

Why

• Fixes behavior reported in detect_deletions runs even when explicitly disabled (v2.0.0) #329 (detect_deletions runs even when disabled).
• Addresses crash-loop behavior from timeout failures in decluttarr crashes on slow server when read times out #317 by making timeout tunable and by preventing one request failure from terminating the full run loop.

Validation

• python3 -m pytest -q
• python3 -m pylint main.py src/job_manager.py src/utils/common.py src/settings/_general.py src/settings/_jobs.py src/settings/_user_config.py tests/jobs/test_job_manager.py tests/settings/test_general.py tests/settings/test_jobs.py tests/utils/test_common.py

[AverageCakeSlice]

Can we please get this merged? Would like to use V2 but this timeout issue is preventing me from connecting to my qbittorrent instance