chore: stop nightly live tests from running on a daily schedule (#478)

The Nightly live channel suite hits ~14 real public endpoints from a shared
CI datacenter IP and asserts each returns results. Public services routinely
rate-limit (429), block datacenter traffic (403) or return transient 5xx, so
at least one fails on nearly every nightly run -- producing a daily false-alarm
failure email with no actionable signal.

Remove the daily cron trigger; keep workflow_dispatch so the suite can still be
run on demand from the Actions tab, where a human can read the result. The job
still fails loudly on any real regression when run.

Authorized by the repo owner (0xmariowu) in lieu of an automated approval gate.

https://claude.ai/code/session_01WJdXSEnHXZ8bhuV33vBN1R

Author: 0xmariowu

.github/workflows/nightly.yml

@@ -1,9 +1,12 @@
 name: Nightly — Live Integration Tests
 
 on:
-  schedule:
-    - cron: "0 2 * * *"   # UTC 02:00 daily
-  workflow_dispatch:       # manual trigger
+  # Daily schedule removed: live tests hit ~14 real public endpoints from a
+  # shared CI IP, so transient upstream rate-limits/blocks (429/403/5xx)
+  # produced a false-alarm failure email nearly every night with no actionable
+  # signal. Run on demand from the Actions tab instead, where a human can read
+  # the result. The job still fails loudly on any real regression.
+  workflow_dispatch:       # manual trigger only
 
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