feat(violet): V4 arm-readiness reporter (PASS MM1)

Read-only aggregation module answering 'is V4 ready to ARM the live canary?'
by consuming gate outcomes into a typed StrictModel report.

Files:
- v4_readiness.py: V4ReadinessReport (6 bool gates + reasons) + assess_v4_readiness()
- test_violet_v4_readiness.py: 13 tests (happy, parametrized single-false,
  hypothesis 2^6 invariant, mutation litmus, StrictModel poison)

Co-Authored-By: mm_VIOLET1 <mm_VIOLET1@h5i>

prod/clean_arch/violet/v4_readiness.py

@@ -0,0 +1,75 @@
+"""V4 arm-readiness reporter — DARK, read-only, non-colliding.
+
+Aggregates V4 gate outcomes into a typed report answering: "is V4 ready
+to ARM the live canary?" Does NOT run gates — CONSUMES their results
+(passed in) and applies fail-closed readiness logic.
+
+Spec: prod/docs/VIOLET_PASS_MM1_V4_READINESS_REPORTER.md
+"""
+
+from __future__ import annotations
+
+from .domain import StrictModel, typed
+
+__all__ = ["V4ReadinessReport", "assess_v4_readiness"]
+
+
+class V4ReadinessReport(StrictModel):
+    """Typed V4 readiness report — all six gates must pass for ready_to_arm."""
+
+    creds_ok: bool
+    canary_passed: bool
+    arming_gate_present: bool
+    conviction_bit_identical: bool
+    selection_parity_ok: bool
+    feed_live: bool
+    reasons: list[str]
+
+    @property
+    def ready_to_arm(self) -> bool:
+        return all((
+            self.creds_ok,
+            self.canary_passed,
+            self.arming_gate_present,
+            self.conviction_bit_identical,
+            self.selection_parity_ok,
+            self.feed_live,
+        ))
+
+
+@typed
+def assess_v4_readiness(
+    *,
+    creds_ok: bool,
+    canary_passed: bool,
+    arming_gate_present: bool,
+    conviction_bit_identical: bool,
+    selection_parity_ok: bool,
+    feed_live: bool,
+) -> V4ReadinessReport:
+    """Build a V4ReadinessReport from gate outcomes. Fail-closed: any False
+    means ready_to_arm is False. No partial-arm."""
+
+    reasons: list[str] = []
+    if not creds_ok:
+        reasons.append("creds_ok: PASS2.1 not satisfied")
+    if not canary_passed:
+        reasons.append("canary_passed: PASS2.3 canary not round-tripped flat")
+    if not arming_gate_present:
+        reasons.append("arming_gate_present: PASS2.2 not satisfied")
+    if not conviction_bit_identical:
+        reasons.append("conviction_bit_identical: PASS2.5 fidelity mismatch")
+    if not selection_parity_ok:
+        reasons.append("selection_parity_ok: PASS2.7/3.1 parity mismatch")
+    if not feed_live:
+        reasons.append("feed_live: PASS2.6 HZ feed stale or deaf")
+
+    return V4ReadinessReport(
+        creds_ok=creds_ok,
+        canary_passed=canary_passed,
+        arming_gate_present=arming_gate_present,
+        conviction_bit_identical=conviction_bit_identical,
+        selection_parity_ok=selection_parity_ok,
+        feed_live=feed_live,
+        reasons=reasons,
+    )