Summary

• Adds gog chat messages reactions create|list|delete to manage emoji reactions on Google Chat messages
• Accepts full resource paths (spaces/.../messages/...) or bare message IDs with --space
• Adds normalizeMessage helper following the same pattern as normalizeThread
• Adds chat.messages.reactions.create and chat.messages.reactions.readonly OAuth scopes to the chat service

Commands

gog chat messages reactions create <message> <emoji> [--space <space>]
gog chat messages reactions list   <message>          [--space <space>]
gog chat messages reactions delete <reaction>

All commands support --json, --dry-run, and --plain flags.

Test plan

• TestNormalizeMessage — covers full path, bare ID + space, missing space, empty, invalid prefix
• TestExecute_ChatMessagesReactionsCreate_JSON — verifies emoji is sent and reaction resource returned
• TestExecute_ChatMessagesReactionsCreate_BareIDWithSpace — verifies bare ID + --space resolves correctly
• TestExecute_ChatMessagesReactionsCreate_ConsumerBlocked — verifies Workspace-only guard
• TestExecute_ChatMessagesReactionsList_JSON — verifies reactions listed with emoji and user
• TestExecute_ChatMessagesReactionsDelete_Text — verifies DELETE request and output
• make ci passes (fmt-check, lint, full test suite)