…ket loss; compute bufferbloat deltas

Implements Tickets #1–#4 to integrate bufferbloat observability, thresholds, parsing, logging, and tests.

- config.py
  - add LATENCY_UNDER_LOAD_THRESHOLD (ms) and SPEEDTEST_PACKET_LOSS_THRESHOLD (%)
  - add BUFFERBLOAT_DELTA_THRESHOLD (ms) for idle→load delta highlighting
- main.py
  - SpeedResults: extend TypedDict with:
    - local_latency_down_load_ms, local_latency_up_load_ms, local_packet_loss_pct
  - run_local_speed_test_task():
    - parse Ookla JSON: download.latency.iqm, upload.latency.iqm, packetLoss (with .get defaults)
    - include parsed metrics in return dict
  - log_results():
    - include new fields in CSV: Local_Load_Down_ms, Local_Load_Up_ms, Local_Pkt_Loss_Pct
    - print bufferbloat lines in console with thresholds:
      - Latency (Download Load), Latency (Upload Load), Speedtest Packet Loss
    - add calculated deltas to CSV/console:
      - Download_Bufferbloat_ms, Upload_Bufferbloat_ms (computed vs idle WAN RTT)
    - consistent float formatting (CSV 3dp; console 2dp for latency, 2dp for %)
  - perform_checks():
    - compute bufferbloat deltas: (under-load latency − idle latency) for down/up
  - run_speed_test_task():
    - improve waiting logic by waiting for the results table (robustness for selenium flow)
  - minor CSV formatting simplification for the data row list comprehension

tests:
- tests/test_core.py
  - update SPEEDTEST_JSON_OUTPUT to include latency.iqm and packetLoss
  - assert parsing of new metrics
  - add test_local_speed_test_parsing_missing_keys (defaults to 0.0 without crash)
- tests/test_logging.py
  - extend MOCK_DATA_COMPLETE with new metrics
  - test_log_results_csv_creation: assert headers include new fields; data row contains “75.500”
  - test_log_results_console_output_highlighting:
    - set thresholds for bufferbloat
    - assert red highlighting for anomalous load latencies and packet loss
  - add boundary test (equal-to-threshold NOT highlighted)
  - add precision tests:
    - CSV: 3dp checks for new fields
    - console: 2dp for latency and packet loss
- tests/test_selenium_tasks.py
  - remains green after switching to table-based wait (ensures stable speed test flow)
  - (adjust mocks to reflect new waiting behavior if needed)

chore: lint, type-check, and verification
- ty check: All checks passed
- ruff check: All checks passed
- pytest: full suite passes locally

Refs: Ticket #1 (config/models), Ticket #2 (Ookla parsing), Ticket #3 (logging/reporting), Ticket #4 (tests)