fix: update Xcode requirement from 26.2 to 26.3

[PureWeen]

Problem

All Mac Catalyst CI builds fail with:

This version of .NET for MacCatalyst (26.2.10233) requires Xcode 26.3.
The current version of Xcode is 26.2.

Root Cause

The .NET MacCatalyst SDK was updated to 26.2.10233 which requires Xcode 26.3. The macos-26 runner has Xcode 26.3 installed at /Applications/Xcode_26.3.app, but our workflows explicitly selected 26.2.

Fix

• release-apps.yml: Both Mac Catalyst jobs updated from xcode-version: '26.2' to '26.3'
• build.yml: Xcode selection fallback updated from 26.2 to 26.3

[github-actions]

🔴 Missed Xcode Version Update — publish-maccatalyst job

Flagged by: 3/3 reviewers | Severity: 🔴 CRITICAL

The PR correctly updates Xcode 26.2 → 26.3 in three places, but misses a fourth — the publish-maccatalyst job in build.yml (lines 78–81) still hardcodes Xcode_26.2:

# .github/workflows/build.yml lines 75-84 (NOT updated by this PR)
      - name: Select Xcode
        run: |
          ls -d /Applications/Xcode*.app 2>/dev/null
          if [ -d "/Applications/Xcode_26.2.app" ]; then        # ← still 26.2
            XCODE_PATH="/Applications/Xcode_26.2.app"           # ← still 26.2
          elif [ -d "/Applications/Xcode_26.2.0.app" ]; then    # ← still 26.2
            XCODE_PATH="/Applications/Xcode_26.2.0.app"         # ← still 26.2

Failing scenario

On push to main or tag push:

1. build-test passes (correctly uses Xcode 26.3)
2. publish-maccatalyst runs, selects Xcode 26.2 (if present on runner), and fails with the exact same .NET for MacCatalyst requires Xcode 26.3 error this PR is fixing

Even if 26.2 isn’t installed, the fix is incomplete — the if/elif checks fall through to the glob fallback, which happens to work but isn’t deterministic.

Suggested fix

Update lines 78–81 to match the build-test job:

          if [ -d "/Applications/Xcode_26.3.app" ]; then
            XCODE_PATH="/Applications/Xcode_26.3.app"
          elif [ -d "/Applications/Xcode_26.3.0.app" ]; then
            XCODE_PATH="/Applications/Xcode_26.3.0.app"

Generated by Expert Code Review (auto) for issue #649 · ◷

[github-actions]

Expert Review Summary

Findings

#	Severity	File	Location	Finding	Consensus
1	🔴 CRITICAL	.github/workflows/build.yml	Lines 78–81 (outside diff)	publish-maccatalyst job still selects Xcode 26.2 — will fail on merge with the same error this PR fixes	3/3 reviewers

Details

The PR updates Xcode 26.2 → 26.3 in the build-test job and both release-apps.yml jobs, but the publish-maccatalyst job in build.yml (lines 78–81) was missed. This job runs on push to main and workflow_dispatch — it will fail with the same .NET for MacCatalyst requires Xcode 26.3 error once merged. See inline comment for the specific fix.

Discarded Findings

• MD_APPLE_SDK_ROOT env var inconsistency (1/3 → cross-examined → discarded): pre-existing difference between jobs, not introduced by this PR, and the build-test job targets net10.0 (not maccatalyst) so the env var is not needed.
• Fallback sort -rV risk (1/3 → cross-examined → discarded): subsumed by Finding 1; fixing lines 78–81 makes this moot.

CI & Test Assessment

• The build-test job (tests) should pass with this PR since the Xcode selection was updated there.
• The publish-maccatalyst job will remain broken until lines 78–81 are also updated.
• No application code changes; no test coverage impact.

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Methodology: 3 independent reviewers with adversarial consensus. Findings confirmed by ≥2/3 reviewers are included. Single-reviewer findings undergo cross-examination by the other 2 before inclusion or discard.

Generated by Expert Code Review (auto) for issue #649