fix(jira): store execution times as real UTC, fix RT date fields, label reopens

- execution_start_time/execution_end_time/detection_time/containment_time
  were captured from a datetime-local input with no local->UTC conversion,
  then stored/displayed as if already UTC — off by the browser's offset.
  Frontend now converts properly in both directions; backend schemas
  defensively normalize any tz-aware input to naive UTC as well.
- push_rt_submitted was pushing datetime.utcnow() (whenever the submit
  button was clicked) into Jira's RT Start/End Date fields instead of the
  operator-entered execution window. Now pushes the *first* round's
  execution start (recovered from round_history across reopens) and the
  *current* round's execution end. Removed push_rt_started, which only
  ever pushed a meaningless click-timestamp.
- Reopening a test now adds a "reopened" Jira label (read-modify-write so
  existing labels aren't clobbered), on top of the existing round-archived
  comment and status push.

backend/app/schemas/test.py

@@ -4,15 +4,29 @@
 import uuid
 
 # Import datetime from datetime
-from datetime import datetime
+from datetime import datetime, timezone
 
-from pydantic import BaseModel, ConfigDict, model_validator
+from pydantic import BaseModel, ConfigDict, field_validator, model_validator
 
 # Import DataClassification from app.domain.enums
 from app.domain.enums import AttackSuccessResult, ContainmentResult, DataClassification
 from app.models.enums import TestResult, TestState
 from app.schemas.evidence import EvidenceOut
 
+
+def _to_naive_utc(v: datetime | None) -> datetime | None:
+    """Normalize an incoming datetime to naive UTC.
+
+    Every timestamp column in this app is naive-UTC (set via
+    ``datetime.utcnow()`` server-side). Clients are expected to send a
+    proper UTC ISO string (with a ``Z``/offset), but if one slips through
+    tz-aware, convert it rather than let it get silently mis-stored as if
+    its clock digits were already UTC.
+    """
+    if v is not None and v.tzinfo is not None:
+        return v.astimezone(timezone.utc).replace(tzinfo=None)
+    return v
+
 # ── Create ──────────────────────────────────────────────────────────
 
 
@@ -85,6 +99,8 @@ class TestRedUpdate(BaseModel):
     execution_start_time: datetime | None = None
     execution_end_time: datetime | None = None
 
+    _normalize_datetimes = field_validator("execution_start_time", "execution_end_time")(_to_naive_utc)
+
 
 # ── Blue Team update ───────────────────────────────────────────────
 
@@ -100,6 +116,8 @@ class TestBlueUpdate(BaseModel):
     # Assign blue_summary = None
     blue_summary: str | None = None
 
+    _normalize_datetimes = field_validator("detection_time", "containment_time")(_to_naive_utc)
+
 
 # ── Round history (archived on reopen) ─────────────────────────────