Emit "time" measure and millisecond values for freshness check diagnostics

[m1n0]

Problem

V4 contract-scan freshness checks render as raw floats (e.g. 11.155277…) in Soda Cloud's check charts instead of a human-readable duration — V3 showed clean unit-bearing values like "X days and Y hours". Two gaps in the freshness diagnostics soda-core sends:

1. No measure/type marker on the value, so Soda Cloud formats it as a plain number.
2. The value is in the check's configured unit (hours/days), but the duration formatter expects milliseconds.

Fix

Align the freshness diagnostics wire payload with the proven V3 soda-library FreshnessCheck contract:

• emit diagnostics.measure = "time" so the value is formatted as a duration
• express diagnostics.value and the fail threshold bounds in milliseconds (scaled from the configured unit)

Implemented via two hooks on CheckResult:

• get_soda_cloud_measure() — None by default, "time" for freshness
• to_soda_cloud_measure_value() — identity by default, unit → ms for freshness

Both default to no-ops, so non-time check payloads are byte-for-byte unchanged.

Tests (written test-first, red → green)

• Unit (test_soda_cloud.py): freshness diagnostics carry measure == "time" and value 3_600_000 ms; non-time checks omit measure.
• Integration (test_freshness_check.py): end-to-end upload payload asserts measure, value in ms, and fail.greaterThanOrEqual in ms.
• Regression: missing / duplicate / row-count diagnostics unchanged.

Formatted with black 23.3.0 (repo-pinned).

Notes

• Freshness is floored to whole-second precision (freshness_in_seconds) before scaling to ms; V3 kept sub-second precision. Negligible for freshness.
• V3 also emitted a warn threshold in ms; V4's diagnostics builder has no warn block today — out of scope here.

🤖 Generated with Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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