Rackpad 1.9.0-beta.2

This beta adds authenticated Uptime Kuma
Prometheus inventory previews and external health mappings. Rackpad V2 remains
deferred. Earlier standalone features and the audit/notification fixes retain
their separate release notes and gates.

Uptime Kuma must expose stable monitor_id labels at authenticated /metrics.
Use an API key as the Basic password, or explicitly supply Basic credentials.
Name-only metrics are rejected with a compatibility message. This adapter never
uses Kuma's internal control API. Monitor status, response time and available
certificate metrics are supported. Pending and maintenance states remain unknown.

Use Imports to preview and explicitly adopt selected inventory, or External health
to refresh readings and bind provider records to existing devices in the same lab.
Ambiguous matches are never bound automatically. Newly adopted devices start with
unknown health. Inventory collection alone does not change device health or alert.
Create a mapped monitor, then explicitly enable it. Degraded values cause alerts
only with the separate degraded-alert opt-in. Other degraded observations remain
visible but count as online for an enabled monitor; this can recover an earlier
unhealthy state. Existing monitor notification delivery, retry and deduplication
apply. Removing or rebinding a source disables its monitors and preserves local
inventory and audit history.

Polling starts disabled. When enabled, its interval is 60–3,600 seconds (initially
60). The cache contains at most 10,000 latest readings per connection and no
telemetry history. A reading is stale after the greater of three intervals or five
minutes. Missing, stale, failed and obsolete observations evaluate as unknown.
Older samples cannot replace newer values. Restart and restore require a fresh
collection before cached observations affect monitors. The page refreshes the
cache display every ten seconds; that display refresh does not contact providers.

Schema is 61. This appends polling settings, provider-record bindings, latest readings
and external monitor mappings. Logical and native recovery validate these records
and lab relationships atomically. Older snapshots default to no polling, bindings
or external monitors. Rollback requires this release's matching pre-upgrade
SQLite database, configuration and encryption-key snapshot; an older executable
must not open the upgraded database.

Validation uses disposable databases, synthetic provider responses and real Kuma
container API acceptance. Physical installation acceptance remains separate. Publication still requires exact
committed CodeQL approval, full MCP/browser and screenshot gates, Net-SNMP
interoperability, Linux storage/user checks, hosted security/quality gates, and
AMD64/ARM64 fresh-install, previous-published-image upgrade, persistence/restart
and paired rollback checks. Verify published revisions and digests before
announcing availability.