fix(ci): remove stale PHASE3_MASKED from all-required sentinel (DISCOVERY #1167)

mc#774 was closed 2026-05-14, re-enabling continue-on-error: false on
platform-build. The PHASE3_MASKED workaround that suppressed platform-build
failures in the sentinel is now stale and was creating a false-green signal
on the all-required CI gate.

Also removes Phase 3 references from comments and success message.

.gitea/workflows/ci.yml

@@ -604,20 +604,17 @@ jobs:
           set -euo pipefail
           # `needs.*.result` is one of: success | failure | cancelled | skipped | null.
           # We assert success per dep (not != failure) — see RFC §2 reasoning above.
-          # Null results are skipped: they come from Phase 3 (continue-on-error: true
-          # suppresses status) or from jobs still in-flight. The sentinel succeeds
-          # rather than blocking PRs on Phase 3 noise.
+          # Null results are skipped: they come from jobs still in-flight.
+          # The sentinel succeeds rather than blocking PRs on transient in-flight noise.
           results='${{ toJSON(needs) }}'
           echo "$results"
           echo "$results" | python3 -c '
           import json, sys
           ns = json.load(sys.stdin)
-          # Phase 3 masked: jobs with continue-on-error: true may report "failure"
-          # Remove when mc#774 handler test failures are resolved.
-          PHASE3_MASKED = {"platform-build"}
-          # Exclude null (Phase 3 suppressed / in-flight) from the bad list.
+          # Phase 3 is over (mc#774 closed 2026-05-14, continue-on-error: false re-enabled).
+          # All non-null/non-skipped/non-cancelled deps must succeed.
           bad = [(k, v.get("result")) for k, v in ns.items()
-                 if v.get("result") not in ("success", None, "cancelled", "skipped") and k not in PHASE3_MASKED]
+                 if v.get("result") not in ("success", None, "cancelled", "skipped")]
           if bad:
               print(f"FAIL: jobs not green:", file=sys.stderr)
               for k, r in bad:
@@ -633,5 +630,5 @@ jobs:
           if cancelled:
               print(f"INFO: {len(cancelled)} job(s) masked by continue-on-error: " +
                     ", ".join(k for k, _ in cancelled), file=sys.stderr)
-          print(f"OK: all {len(ns)} required jobs succeeded (or Phase-3 suppressed)")
+          print(f"OK: all {len(ns)} required jobs succeeded")
           '