fix(twitch): reject invalid IRC timestamps

[aiirvizionz]

Summary

• reject non-decimal, unsafe, and out-of-range Twitch IRC timestamps
• fall back to the current time instead of throwing while converting an invalid Date
• isolate timestamp parsing so malformed IRC tags can be tested without a live connection

Root cause

Number.isFinite() does not guarantee that a numeric value can be represented as a valid JavaScript Date. A finite tmi-sent-ts value outside the supported date range reached toISOString() and threw while processing an incoming Twitch message. Numeric formats that Twitch does not emit, such as exponent or fractional notation, were also accepted.

Verification

• 9 focused Vitest cases pass for valid, missing, malformed, unsafe, and out-of-range values
• git diff --check

The full workspace install/typecheck is currently blocked by the checked-in lockfile entry for @profullstack/autoblog@0.4.0, whose tarball has no integrity metadata. GitHub CI remains the authoritative full-repository check.

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

[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.