Add `blocking.loading.refreshPeriod` to control blocklist refresh interval

[robocopklaus]

Summary

Blocky refreshes downloaded blocklists periodically, but the refresh interval cannot currently be configured through the addon UI. Blocky's default is 4 hours.

Blocky Config Key

blocking.loading.refreshPeriod: <duration>

Use Case

• Reduce refresh frequency: Users on metered connections or with many large blocklists can reduce unnecessary bandwidth usage (e.g., set to 24h or 168h)
• Increase refresh frequency: Security-conscious users may want more frequent updates to get the latest threat intelligence (e.g., 1h)
• Disable refreshing: Set to 0 to only load blocklists on startup

This is the most impactful blocking.loading sub-option for typical users. The full blocking.loading subsection (downloads, concurrency, strategy) is more complex and may be better suited for custom config mode.

Proposed Change

config.yaml:

blocking:
  loading:
    refresh_period: 4h
# schema:
blocking:
  loading:
    refresh_period: str?

blocky.gtpl:

{{- if $blocking.loading.refresh_period }}
  loading:
    refreshPeriod: {{ $blocking.loading.refresh_period | quote }}
{{- end }}

References

• Blocky configuration reference - blocking.loading