Add default initialization for RELEASE_TYPE to handle edge cases

[Copilot]

Addresses feedback on PR #1095 regarding uninitialized RELEASE_TYPE variable when LATEST_TAG is empty or null.

Changes

• Initialize RELEASE_TYPE = "preminor" at script start (line 48) before tag retrieval
• Ensures valid output to GITHUB_OUTPUT at line 127 in all code paths

Context

Without initialization, fresh repositories with no tags or failed tag retrieval would leave RELEASE_TYPE undefined:

# Before: RELEASE_TYPE only set inside conditionals
$LATEST_TAG = git tag -l --sort=-version:refname | Select-Object -First 1
if ($LATEST_TAG -like "*-*") {
    $RELEASE_TYPE = "prerelease"
} else {
    $RELEASE_TYPE = "preminor"
}
# If LATEST_TAG is empty, RELEASE_TYPE remains uninitialized

# After: Default value guarantees valid output
$RELEASE_TYPE = "preminor"  # Safe default
$LATEST_TAG = git tag -l --sort=-version:refname | Select-Object -First 1
# Conditionals update if tag exists, otherwise default is used

Default of "preminor" is appropriate for first prerelease version creation.

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[Copilot]

Pull request overview

This PR adds defensive initialization for the RELEASE_TYPE variable to ensure it always has a valid value before being written to GITHUB_OUTPUT. The change sets a default value of "preminor" at the beginning of the script, which is appropriate for creating the first prerelease version.

Key Changes:

• Added default initialization $RELEASE_TYPE = "preminor" at line 48, immediately before tag retrieval
• Ensures valid output is written to GITHUB_OUTPUT at line 130 in all code paths