Reorder notebook metadata and tweak markdown

Move nbformat and metadata blocks to the end of claude/lab02_task3_git_activity.ipynb, normalize whitespace/blank lines, replace em-dash characters with ASCII double-hyphens in markdown, and add an explicit <br> for spacing. Pure formatting and markdown cleanups to keep the notebook structure consistent.

claude/lab02_task3_git_activity.ipynb

@@ -1,12 +1,5 @@
 {
- "nbformat": 4,
- "nbformat_minor": 5,
- "metadata": {
-  "kernelspec": {"display_name": "Python 3", "language": "python", "name": "python3"},
-  "language_info": {"name": "python", "version": "3.10.0"}
- },
  "cells": [
-
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -20,7 +13,7 @@
     "\n",
     "### Context\n",
     "\n",
-    "You have been handed an activity log from a Git-based classroom platform. It records **10,000 events** — commits, pull requests, CI runs, code reviews, and test runs — generated by students and bots across multiple repositories.\n",
+    "You have been handed an activity log from a Git-based classroom platform. It records **10,000 events** -- commits, pull requests, CI runs, code reviews, and test runs -- generated by students and bots across multiple repositories.\n",
     "\n",
     "Your goal is to apply the same EDA and cleaning pipeline from Task 2 to this new dataset. This time the guidance is lighter: each section tells you *what* to look for and *which tools and methods to use*, but the code is yours to write.\n",
     "\n",
@@ -37,7 +30,6 @@
     "---"
    ]
   },
-
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -149,7 +141,9 @@
     "| `pr_merge_time_hours` min | Any negative values? |\n",
     "| `commit_message_length` min | Any zero values? What would a zero-length commit message mean? |\n",
     "\n",
-    "> **Note on `pr_merge_time_hours`:** Think carefully about why this column has so many missing values before deciding what to do. Look at the `event_type` column for rows where it is missing — does a pattern emerge?\n",
+    "<br>\n",
+    "\n",
+    "> **Note on `pr_merge_time_hours`:** Think carefully about why this column has so many missing values before deciding what to do. Look at the `event_type` column for rows where it is missing -- does a pattern emerge?\n",
     "\n",
     "*(Record any additional observations below)*\n",
     "\n",
@@ -671,6 +665,18 @@
     "*(Double-click to write your answers)*"
    ]
   }
-
- ]
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "name": "python",
+   "version": "3.10.0"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
 }