feat(issues): add --type flag to update command

[piekstra]

Summary

Closes #149

• Adds --type / -t flag to jtk issues update for changing an issue's type without requiring jtk issues move
• Uses the Jira Cloud bulk move API transparently — the user doesn't need to know about the move workaround
• Skips the operation if the issue already has the requested type
• Can be combined with other update flags (--summary, --description, etc.)

Usage

# Change issue type (previously required: jtk issues move MON-123 --to-project MON --to-type Task)
jtk issues update MON-123 --type Task

# Combine with other updates
jtk issues update MON-123 --type Story --summary "Updated title"

Test plan

• TestRunUpdate_TypeChange verifies the move API is called with correct project/type mapping
• TestRunUpdate_TypeAlreadyCorrect verifies no-op when type is unchanged
• TestNewUpdateCmd verifies the --type flag exists with -t shorthand
• All existing update tests pass with updated function signature
• golangci-lint run clean