feat(root02): author Linux Administration & Networking

Adds all 6 ROOT 02 modules (Linux system administration, storage & filesystems, the
Networking Mental Model, Linux network inspection, DNS & HTTP, Linux troubleshooting) — 37
activities, each with a real lesson, demonstration/guided exercise, knowledge check, hands-on
Lab, and reflection. The Networking Mental Model module (M3) gets deliberately extra depth per
its "critical module" designation, with no lab by design — conceptual mastery via knowledge
check and guided exercise, matching root-05-m00's own precedent.

Adds 6 new hands-on Linux/networking scenarios plus 2 MCQs: linux-service-inspection (inspects
the platform's own real nginx without touching it — a genuinely safe, real service-inspection
target that avoids ever risking the Lab's own connectivity), linux-service-lifecycle (start/
verify/stop a fully controllable service), linux-storage-inspection, linux-network-inspection
(ip/ss/getent/curl, each framed as answering one specific diagnostic question),
linux-dns-http-diagnosis (a genuine DNS-resolves-but-wrong-port failure, diagnosed and fixed),
and linux-troubleshooting-framework (a real missing-config-file failure, resolved via the
RootNode Observe/Evidence/Hypothesis/Test/Repair/Validate/Prevent framework). All tested
end-to-end via the real scenario-validation API, including negative tests confirming they fail
when unsolved.

Wires rootnode-linux-networking-assessment (2 required + 4 random-draw scenarios) using the
existing Phase 3B assessment engine.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

scenarios/data/linux-storage-inspection.json

@@ -0,0 +1,37 @@
+{
+  "id": "linux-storage-inspection",
+  "title": "Find What's Actually Using the Disk",
+  "category": "Linux Administration",
+  "isolation_type": "shared_namespace",
+  "difficulty": "Easy",
+  "type": "task",
+  "weight": 4,
+  "description": "## Find What's Actually Using the Disk\n\nThree directories under `/srv/storage-lab/` (`logs`, `cache`, `data`) contain different amounts of data. \"It's probably the logs\" is a guess — find the real answer.\n\n**Your task:**\n\n1. Use `du` to measure the actual size of each of the three directories\n2. Use `df` to check overall filesystem usage on `/`\n3. Write the name of the directory (just `logs`, `cache`, or `data`) that uses the MOST space to `/srv/storage-lab/biggest.txt`",
+  "hints": [
+    {
+      "title": "Measuring each directory",
+      "body": "`du -sh <dir>` summarizes total size for one directory. Run it against all three, or use a wildcard to see them side by side.",
+      "command": "du -sh /srv/storage-lab/*/"
+    },
+    {
+      "title": "Overall filesystem usage",
+      "body": "`df -h /` shows total/used/available space for the filesystem root lives on — a different, complementary question from `du` (which measures a specific directory's contents).",
+      "command": "df -h /"
+    }
+  ],
+  "setup_commands": [
+    { "command": "mkdir -p /srv/storage-lab/logs /srv/storage-lab/cache /srv/storage-lab/data" },
+    { "command": "dd if=/dev/zero of=/srv/storage-lab/logs/app.log bs=1M count=1 2>/dev/null" },
+    { "command": "dd if=/dev/zero of=/srv/storage-lab/cache/blob.bin bs=1M count=10 2>/dev/null" },
+    { "command": "dd if=/dev/zero of=/srv/storage-lab/data/small.txt bs=1K count=2 2>/dev/null" }
+  ],
+  "validation": {
+    "commands": [
+      { "description": "correctly identified cache/ as the largest consumer", "command": "cat /srv/storage-lab/biggest.txt", "expected_output": "cache", "match": "exact" }
+    ]
+  },
+  "default_namespace": "default",
+  "teardown_commands": [
+    { "command": "rm -rf /srv/storage-lab" }
+  ]
+}