fix(plugins): sync TableProCore PluginKit SSLHandshakeError with the framework

[datlechin]

Problem

The "Shared contract drift" CI gate (scripts/audit-refactor-health.sh --check) fails on every PR cut from current main:

❌ new PluginKit divergence not in baseline: SSLHandshakeError.swift

SSLHandshakeError exists in two PluginKit trees that are kept byte-identical until consolidation:

• Plugins/TableProPluginKit/SSLHandshakeError.swift (framework, canonical)
• Packages/TableProCore/Sources/TableProPluginKit/SSLHandshakeError.swift (package copy)

#1520 added three client-key cases to the framework copy (clientKeyPassphraseRequired, clientKeyPassphraseIncorrect, clientKeyInvalid) but didn't mirror them into the package copy, so the two drifted. The baseline doesn't list the file, and its header says not to baseline fresh divergence, so the right fix is to re-sync.

Fix

Add the three missing cases to the package copy so it matches the framework contract byte for byte. No behavior change on the desktop app (it builds against the framework copy, which already had them); this restores the package/TableProCore copy that the gate compares.

Verified locally:

$ scripts/audit-refactor-health.sh --check
  ✅ no new shared-contract drift beyond .github/duplicate-contract-baseline.txt
✅ drift gates passed

This unblocks the drift gate for all open PRs, not just one.