Mutation check done on all accepted tasks; mutant fixes; dump filter in proxy

- skip sy-subrc lines and CDS type lengths; CDS literal mutants; mutate helper classes
- proxy: sap_short_dumps shows only dumps of the current run
- 26/26 tasks pass; results in docs/faz1-tasarim.md 11g

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014aUaQeLnwbb1zTpN7kHeat

tasks/T15/mutation.json

@@ -0,0 +1,39 @@
+{
+ "task": "T15",
+ "mutants": [
+  {
+   "object": "{{P}}I_ORDER_TOTAL",
+   "mutant": "line 5: inner join -> left outer join (join)",
+   "status": "killed",
+   "hidden": "4/5",
+   "failed_tests": [
+    "ORDER_WITHOUT_ITEMS"
+   ]
+  },
+  {
+   "object": "{{P}}I_ORDER_TOTAL",
+   "mutant": "line 5: = -> <> (eq)",
+   "status": "killed",
+   "hidden": "1/5",
+   "failed_tests": [
+    "DECIMALS",
+    "ITEM_COUNTS",
+    "ORDER_WITHOUT_ITEMS",
+    "TOTALS"
+   ]
+  },
+  {
+   "object": "{{P}}I_ORDER_TOTAL",
+   "mutant": "line 10: sum( -> max( (agg)",
+   "status": "killed",
+   "hidden": "4/5",
+   "failed_tests": [
+    "TOTALS"
+   ]
+  }
+ ],
+ "valid": 3,
+ "killed": 3,
+ "kill_rate": 1.0,
+ "ok": true
+}