Add OutageDeck monitoring mixin

[koko3tallah]

Adds the OutageDeck monitoring mixin to the public catalog.

The mixin is maintained in https://github.com/outagedeck/prometheus-exporter/tree/main/mixin and provides:

• six configurable Prometheus alerts for provider and service disruptions, failed refreshes, unknown status, and stale source data
• the existing nine-panel OutageDeck Grafana dashboard
• configurable alert durations, source-staleness threshold, and severities

Validation performed:

• exporter CI is green: https://github.com/outagedeck/prometheus-exporter/actions/runs/30976012974
• jsonnet evaluation produced six unique alert rules
• generated alerts pass promtool check rules
• generated dashboard matches the maintained dashboard semantically
• this repository's own Linux generate target produced the alert documentation, alerts YAML, and dashboard successfully

[koko3tallah]

I rechecked the red Netlify status separately from the catalog change. Netlify's public deploy record (6a72c2021ec1c90008b1d621) entered error before a build ran: it reports no deploy time, error message, or public build log. The branch is one commit ahead of the current master and has no base drift.

The repository's Linux generation path completed successfully for this entry and produced the OutageDeck alert documentation, six-rule alert YAML, and dashboard; the generated alerts also pass promtool check rules. I therefore have not pushed a speculative content change or empty retry commit. The remaining red status appears to require a Netlify-side retry or log access rather than a source patch.

[koko3tallah]

Follow-up commit a7f02d1 adds the deterministic generated outputs for this catalog entry rather than relying on the next daily regeneration:

• six-rule alert YAML and the expected empty recording-rule file
• the nine-panel Grafana dashboard
• the generated OutageDeck site page
• the static mixins.json mirror used by the published site

Validation after the commit:

• Prometheus promtool 3.13.2: SUCCESS: 6 rules found and SUCCESS: 0 rules found
• generated dashboard is semantically identical to the first-party source dashboard
• both catalog JSON files contain the exact OutageDeck source/subdirectory tuple
• Hugo 0.70.0 extended, matching netlify.toml, builds all 221 pages and renders the OutageDeck alerts/dashboard page
• git diff --check passes

The exact Hugo build also exposed the repository-wide cause of the Netlify pre-build failure: .gitmodules points to the now-missing vantagedesign/ace-documentation repository. The same pinned commit (2415924) remains available in emixs/ace-documentation; overriding only the local submodule URL to that surviving fork makes the exact-version build pass. I did not mix that repository-maintenance change into this focused catalog PR.