v2 Standard: Multiline String API for Triggers

[DerekRoberts]

Summary\n\nWe have officially decided to move from the heritage 'Bash-Array' syntax ('...' '...') to a standard Multiline String API for all trigger inputs in the consolidated re-launch.\n\n### Why Multiline String?\n1. Maximum Predictability: GitHub preserves newlines exactly, ensuring we never have to guess how the string was constructed.\n2. Backend Simplicity: We can parse this using a simple while read -r loop in Bash, eliminating fragile grep patterns.\n3. Approachability: It is the standard way to handle lists in many other actions (like paths-filter).\n\n### Example Action v2:\nyaml\nwith:\n triggers: |\n ./src/\n ./tests/\n ./Containerfile\n