test: cover Uptime Kuma status normalization matrix

[shivros]

Summary

Adds compact table-driven parser regression coverage for all supported Uptime Kuma heartbeat statuses:

• 0 → down / critical
• 1 → up / info
• 2 → pending / warning
• 3 → maintenance / info

Each case verifies normalized source, event type, action, severity, and retained metadata. Existing signature and malformed/unknown-status failure coverage remains intact.

Verification

cargo test -p rite-sources uptime_kuma
cargo build --all-targets
cargo test --all-targets
cargo clippy --all-targets -- -D warnings
cargo fmt --all -- --check
cargo run -p rite-codegen -- check

All passed locally.

Closes COD-472.

[shivros]

🤖 Automated Review Panel

Reviewer A — GPT-5.6-terra

APPROVE — exact table-driven parser matrix covers all four declared statuses and required normalized fields; existing negative coverage is retained.

Reviewer B — Gemini 3 Flash

APPROVE — no substantive correctness or goal-alignment concerns.

The first review transcription incorrectly escaped quotes inside the raw Rust string; it was discarded and both reviewers re-ran against the exact source shown in this PR.

[shivros]

Auto-Merge Gate

Confidence: 0.97

This is a narrowly scoped regression-evidence change for COD-472. The diff replaces the single successful-status assertion with a table-driven matrix covering all four documented Uptime Kuma statuses while preserving signature verification and existing negative tests.

Checks observed: CI test and Creed context drift completed successfully.

Scope limits: one test module; no production behavior, credentials, public-surface, deployment, or data-handling changes.