ci: retry test-product downloads and fix shared CI failures

[datlechin]

#3208's UI tests 2/3 failed before running a test: actions/download-artifact gave up on the test-products artifact with "Artifact download failed after 5 retries" (a blob storage error), and the shard failed the whole gate.

Change

unpack-test-products now tries the download, and if that step fails, waits 60 seconds and tries once more. The action's own five retries span about half a minute, which that outage outlasted. When the first attempt succeeds, nothing changes. A second failure still fails the job, as before.

The artifact retry itself has no CHANGELOG entry. The shared Safe Mode fix below has an Unreleased entry.

CI fixes

The failed Package Tests job was SyncRecordMapperTests.unknownWireValueFailsClosed: the sync mapper's duplicate decoder turned an unknown Safe Mode value into Off. It now uses SafeModeLevel(wireValue:isReadOnly:), requiring confirmation while retaining legacy read-only restrictions. Added regressions for unknown read-only values and renames that preserve an unknown wire value.

Integrated main, preserving both sets of changelog entries. Fixed the confirmed SurrealDB compile error introduced by the integration: text called a length-taking JSON helper that had become a property. Restored that helper, retaining valid display truncation and complete export text.

Validation for these fixes:

• Full swift test --package-path Packages/TableProCore: passed (1,197 Swift Testing tests plus XCTest).
• SwiftLint on the changed Swift files: zero violations. The helper's documentation check still flags four pre-existing stale paths: TableProApp/rust-dameng, Contents/MacOS, Contents/Helpers, and /Applications/Xcode-beta.app.
• Project regeneration: passed.
• The three updated branches have identical SurrealDB sources and driver tests. An isolated SwiftPM build of all those plugin sources and the actual driver test file passed 50 tests in 8 suites on ci: retry test-product downloads and fix shared CI failures #3216. The identical corrected helper also passed an AllPlugins Xcode build earlier on fix(plugin-surrealdb): BETWEEN, REGEX and IS EMPTY filters become equality checks #3218.

GitHub Actions rerun after pushing these fixes.