fix(util): make objectOfArraysAsArrayOfObjects work with native array methods

[sroussey]

Problem

The objectOfArraysAsArrayOfObjects proxy backs onto an empty [], so HasProperty for a numeric index returned false. Native array methods that probe presence (slice, concat, at, flat, …) therefore treated every row as an absent hole and silently dropped the data:

const p = objectOfArraysAsArrayOfObjects({ a: [1,2,3,4], b: ["w","x","y","z"] });
p.slice(0, 2)        // -> [ 2 x empty items ]  (sparse!)
[...p.slice(0, 2)]   // -> [ undefined, undefined ]
p.map(r => r.a)      // -> [1,2,3,4]  (map is explicitly implemented, so it worked)

This surfaced downstream in @workglow/sec, where StoreSubmissionFilingsTask sliced the proxy to batch filings and then spread the result into a bulk insert — every filing became an undefined row and the insert crashed, storing zero filings. (That caller has its own fix; this is the root cause.)

Fix

• Add a has trap that reports in-range numeric indices (and length) as present, so native methods that rely on HasProperty see real rows.
• Implement slice explicitly, mirroring the file's other materializing methods (map/filter/forEach/…) and guarding the exact method that regressed.

Test

Regression cases (slice returns dense rows, the in operator, at/concat) added to the existing proxy suite in the dedicated @workglow/test package (packages/test/src/test/util/arrayAsObjectProxy.test.ts) — 14 pass against a freshly built @workglow/util.

🤖 Generated with Claude Code

https://claude.ai/code/session_01BNNJyBunCkJhiUhdM9ys7V

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	62.83%	25680 / 40872
🔵	Statements	62.66%	26569 / 42400
🔵	Functions	64.03%	4874 / 7612
🔵	Branches	51.56%	12590 / 24416

File Coverage

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