fix(query): widen the wasm32 clock past Int32.max to survive long uptime

[zzal]

Part II Wave 1 · #1 — wasm32 clock trap at ~25 days of uptime

SystemQueryClock.now() read performance.now() and returned .milliseconds(Int(ms)). performance.now() grows monotonically from navigation start; on wasm32 Int is 32-bit, so Int(ms) traps — killing the whole app — once page uptime passes Int32.max ms ≈ 24.85 days. That's exactly the long-lived dashboard workload the cache is built for (MissionControl models it).

Invisible to every existing gate: the host's Int is 64-bit, and the type was smoke-tested in the browser, not unit-tested. (Its sibling RetryPolicy.delay was scrupulously overflow-proven; this one narrowing slipped through — the [[wasm32-int-32bit]] footgun.)

Fix

Extract a pure, host-testable conversion and widen through Int64:

static func duration(millisecondsSinceOrigin ms: Double) -> Duration {
    .milliseconds(Int64(exactly: ms.rounded()) ?? .max)
}

• Int64 widening removes the 32-bit trap (Int64.max ms ≈ 2.9e8 years — unreachable).
• Int64(exactly:) ?? .max also absorbs a non-finite reading (which traps even on the host) into a benign maximally-stale → refetch, never a crash.
• Extracted, not inlined in now(), precisely so the rules can be pinned by host tests the browser-only path can't otherwise reach.

Tests

3 new host tests in ClockTests:

• widens past Int32.max (2^31 boundary + a 30-day uptime)
• rounds a sub-millisecond reading to the nearest ms
• clamps .infinity / .nan to .max instead of trapping

Verification

• New Clock tests 4/4 pass.
• Full host suite green: 1373 tests, 275 suites.
• QueryDemo wasm build clean — compiles the #if canImport(JavaScriptKit) branch that actually carries the fix.

🤖 Generated with Claude Code

[github-actions]

📦 Bundle size

Artifact	Baseline	This PR	Δ
App.wasm	5.06 MB	5.15 MB	+1.90%
App.wasm (gzip)	1.80 MB	1.84 MB	+2.21%
JS runtime	54.5 KB	54.5 KB	+0.00%
JS runtime (gzip)	11.3 KB	11.3 KB	+0.00%
Total (gzip)	1.81 MB	1.85 MB	+2.19%

✅ Within budget (≤5% growth allowed).

_{Baseline: Swift 6.3, WASM SDK 6.3-RELEASE, measured 2026-06-18.}