feat: replace heuristic LOC estimates with precise cloc counts for all benchmark repos

The old repo_approx_loc was computed as repo_size_bytes/30, which inflated
values by 5-50x (e.g. linux: 208M heuristic vs 29.8M actual). Now uses
cloc --json on shallow clones of all 71 repos.

- Add scripts/collect_repo_cloc.py: shallow-clone + cloc pipeline (resumable)
- Add scripts/update_loc_from_cloc.py: propagate cloc values to all configs
- Update backfill_size_metadata.py to prefer cloc data over bytes/30 heuristic
- Update 470/477 tasks across 9 config files + official_results.json
- 71 repos counted: 9.9K (grpcurl) to 43.4M (chromium) code lines

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sjarmak

configs/coverage_gap_tasks.json

@@ -23,7 +23,7 @@
       "repo_size_mb": 2439.537,
       "repo_file_count": 20583,
       "repo_directory_count": 3599,
-      "repo_approx_loc": 85268002,
+      "repo_approx_loc": 7111004,
       "repo_languages": [
         {
           "language": "csharp",
@@ -52,7 +52,31 @@
       "repo_complexity_source": "cached_registry",
       "task_complexity": 0.15,
       "task_complexity_label": "medium",
-      "task_complexity_source": "ground_truth_meta_plus_registry"
+      "task_complexity_source": "ground_truth_meta_plus_registry",
+      "repo_approx_loc_source": "cloc",
+      "repo_cloc_total_files": 19850,
+      "repo_cloc_top_languages": [
+        {
+          "language": "C#",
+          "code_lines": 4582333
+        },
+        {
+          "language": "Visual Basic .NET",
+          "code_lines": 1709980
+        },
+        {
+          "language": "XML",
+          "code_lines": 668001
+        },
+        {
+          "language": "JSON",
+          "code_lines": 77418
+        },
+        {
+          "language": "Markdown",
+          "code_lines": 28473
+        }
+      ]
     },
     {
       "task_id": "ccx-migration-294",
@@ -73,7 +97,7 @@
       "repo_size_mb": 2881.666,
       "repo_file_count": 81361,
       "repo_directory_count": 2195,
-      "repo_approx_loc": 100721527,
+      "repo_approx_loc": 3030308,
       "repo_languages": [
         {
           "language": "typescript",
@@ -92,7 +116,31 @@
       "repo_complexity_source": "cached_registry",
       "task_complexity": 0.15,
       "task_complexity_label": "medium",
-      "task_complexity_source": "ground_truth_meta_plus_registry"
+      "task_complexity_source": "ground_truth_meta_plus_registry",
+      "repo_approx_loc_source": "cloc",
+      "repo_cloc_total_files": 37623,
+      "repo_cloc_top_languages": [
+        {
+          "language": "JavaScript",
+          "code_lines": 1870486
+        },
+        {
+          "language": "TypeScript",
+          "code_lines": 676704
+        },
+        {
+          "language": "XML",
+          "code_lines": 254275
+        },
+        {
+          "language": "Markdown",
+          "code_lines": 179456
+        },
+        {
+          "language": "JSON",
+          "code_lines": 46297
+        }
+      ]
     }
   ]
-}
+}

configs/rerun_2_failed_org.json

@@ -23,7 +23,7 @@
       "repo_size_mb": 2881.666,
       "repo_file_count": 81361,
       "repo_directory_count": 2195,
-      "repo_approx_loc": 100721527,
+      "repo_approx_loc": 3030308,
       "repo_languages": [
         {
           "language": "typescript",
@@ -42,7 +42,31 @@
       "repo_complexity_source": "cached_registry",
       "task_complexity": 0.15,
       "task_complexity_label": "medium",
-      "task_complexity_source": "ground_truth_meta_plus_registry"
+      "task_complexity_source": "ground_truth_meta_plus_registry",
+      "repo_approx_loc_source": "cloc",
+      "repo_cloc_total_files": 37623,
+      "repo_cloc_top_languages": [
+        {
+          "language": "JavaScript",
+          "code_lines": 1870486
+        },
+        {
+          "language": "TypeScript",
+          "code_lines": 676704
+        },
+        {
+          "language": "XML",
+          "code_lines": 254275
+        },
+        {
+          "language": "Markdown",
+          "code_lines": 179456
+        },
+        {
+          "language": "JSON",
+          "code_lines": 46297
+        }
+      ]
     }
   ]
-}
+}