fix(social-telegram): tolerate missing message date

[aiirvizionz]

Summary

• avoid throwing after a successful Telegram sendMessage response when the message date is missing or unusable
• fall back to the current timestamp for publishedAt
• add regression coverage for successful responses without a date

Tests

• vitest run packages/social/telegram/src/index.test.ts
• tsc -p packages/social/telegram/tsconfig.json --noEmit

[github-actions]

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[github-actions]

🤖 Auto-rebase: The branch was rebased successfully locally but could not be pushed to the fork. Please enable 'Allow edits from maintainers' in the PR settings, or rebase manually: git fetch upstream master && git rebase upstream/master.

[github-actions]

🤖 Auto-rebase: The branch was rebased successfully locally but could not be pushed to the fork. Please enable 'Allow edits from maintainers' in the PR settings, or rebase manually: git fetch upstream master && git rebase upstream/master.

[github-actions]

🤖 Auto-rebase: The branch was rebased successfully locally but could not be pushed to the fork. Please enable 'Allow edits from maintainers' in the PR settings, or rebase manually: git fetch upstream master && git rebase upstream/master.