feat: Enhance case collection and detail forms with timing overrides and custom screens

Co-authored-by: Copilot <copilot@github.com>

atlas/models.py

@@ -1360,6 +1360,10 @@ class CaseCollection(ExamOrCollectionGenericBase):
         default=True,
         help_text="Enable per-case query and messaging for this collection.",
     )
+    show_results_sharing_information = models.BooleanField(
+        default=True,
+        help_text="If true, show result-sharing information on candidate start and overview screens.",
+    )
 
     question_time_limit = models.PositiveIntegerField(
         blank=True,
@@ -1367,6 +1371,39 @@ class CaseCollection(ExamOrCollectionGenericBase):
         help_text="Time limit for answering questions in seconds."
     )
 
+    answer_entry_grace_period = models.PositiveIntegerField(
+        blank=True,
+        null=True,
+        default=0,
+        help_text="Additional seconds after the case view is locked during which answers can still be entered."
+    )
+
+    start_screen_content = models.TextField(
+        blank=True,
+        null=True,
+        help_text="Optional HTML content shown on the collection start screen (for example embedded resources).",
+    )
+
+    start_screen_resources = models.ManyToManyField(
+        "Resource",
+        blank=True,
+        related_name="start_screen_collections",
+        help_text="Optional resources shown on the collection start screen.",
+    )
+
+    end_overview_content = models.TextField(
+        blank=True,
+        null=True,
+        help_text="Optional HTML content shown on the collection end overview screen.",
+    )
+
+    end_overview_resources = models.ManyToManyField(
+        "Resource",
+        blank=True,
+        related_name="end_overview_collections",
+        help_text="Optional resources shown on the collection end overview screen.",
+    )
+
     # Collections that must be completed before this collection can be taken
     prerequisites = models.ManyToManyField(
         "self",
@@ -1480,6 +1517,16 @@ class CaseCollection(ExamOrCollectionGenericBase):
         """Returns the cases in the collection in order of the CaseDetail sort_order"""
         return self.cases.all().order_by("casedetail__sort_order")
 
+    def get_effective_case_time_limit(self, casedetail):
+        if casedetail.question_time_limit_override is not None:
+            return casedetail.question_time_limit_override
+        return self.question_time_limit
+
+    def get_effective_answer_entry_grace_period(self, casedetail):
+        if casedetail.answer_entry_grace_period_override is not None:
+            return casedetail.answer_entry_grace_period_override
+        return self.answer_entry_grace_period or 0
+
     def get_next_case(self, case):
         cases = list(self.get_cases())
 
@@ -1707,6 +1754,18 @@ class CaseDetail(models.Model):
         help_text="This will override the case history for the purpose of the exam/collection."
     )
 
+    question_time_limit_override = models.PositiveIntegerField(
+        null=True,
+        blank=True,
+        help_text="Optional per-case override for the answer time limit in seconds.",
+    )
+
+    answer_entry_grace_period_override = models.PositiveIntegerField(
+        null=True,
+        blank=True,
+        help_text="Optional per-case override for additional answer-only time in seconds after case view lock.",
+    )
+
     class Meta:
         ordering = ("sort_order",)