fix(rectification): anchor candidate windows to civil dates across midnight

Carry explicit local date intervals instead of inferring the day from clock
order. Cluster width, delivery, adoption, and reports keep the actual civil
date; adopted date is stored separately from the reported birth_date.

Algorithm identity is scoring-9 / spec-v5. Scoring weights, confirmation
thresholds, and Skill version are unchanged. Isolated Linux final-3 gates
passed; four pre-existing Python failures remain. This is not a production
release.

scripts/rectification/contracts.py

@@ -53,7 +53,7 @@ _EVENT_PROVENANCE_FIELDS = frozenset({
 _REQUEST_FIELDS = frozenset({
     "birth_date", "start_time", "end_time", "lat", "lon", "tz", "events",
     "ayanamsa", "node_mode", "asked_probe_keys", "declined_domains", "column_times", "minute_step", "blocks",
-    "refresh_probes",
+    "refresh_probes", "candidate_intervals",
 }) | _REQUEST_PROVENANCE_FIELDS
 ASKED_PROBE_KEY_MAX_LENGTH = 200
 _EVENT_FIELDS = frozenset({"id", "domain", "event_kind", "date_start", "date_end", "precision", "summary"}) | _EVENT_PROVENANCE_FIELDS
@@ -175,6 +175,7 @@ class RectificationRequest(TypedDict):
     refresh_probes: NotRequired[bool]
     minute_step: NotRequired[int]
     blocks: NotRequired[list[dict[str, Any]]]
+    candidate_intervals: NotRequired[list[dict[str, str]]]
 
 
 JsonObject = dict[str, Any]
@@ -406,4 +407,7 @@ def normalize_rectification_request(body: Any, *, today: date | None = None) ->
             cleaned_request["minute_step"] = minute_step
     if "blocks" in body:
         cleaned_request["blocks"] = _normalize_blocks(body, start_time, end_time)
+    if "candidate_intervals" in body:
+        from scripts.rectification.candidate_window import candidate_intervals
+        cleaned_request["candidate_intervals"] = candidate_intervals(body)
     return cast(RectificationRequest, cleaned_request)