Stabilize dev pre-commit workflow

Add fallback hook dependencies in validate-dev and apply trailing-whitespace fixes to lab plan files so pre-commit no longer fails on auto-modifications.

.github/workflows/book-validate-dev.yml

@@ -106,7 +106,7 @@ jobs:
           echo "📦 Installing project dependencies for custom hooks..."
           pip install -r requirements.txt || echo "⚠️ Could not install all requirements, continuing..."
           echo "📦 Installing fallback hook dependencies..."
-          pip install rich || echo "⚠️ Could not install rich, continuing..."
+          pip install rich requests pillow pint || echo "⚠️ Could not install one or more fallback deps, continuing..."
           
           echo "🔧 Installing pre-commit hooks..."
           pre-commit install --install-hooks

labs/plans/vol1/lab_02_ml_systems.md

@@ -36,7 +36,7 @@
 ## 3. The 3-Act Narrative (The Lab Journey)
 
 ### Act I: Proving the Iron Law (15m)
-*   **Scenario:** You have a fixed model ($AI = 50$). 
+*   **Scenario:** You have a fixed model ($AI = 50$).
 *   **Crisis:** It runs too slow on the CPU.
 *   **Task:** Upgrade to a GPU. Observe that the latency *barely moves* because the data term ($D/BW$) is the bottleneck. Find the "Ridge Point" where the GPU actually becomes useful.
 

labs/plans/vol1/lab_04_data_engr.md

@@ -37,7 +37,7 @@
 
 ### Act I: The Physics of Data Gravity (15m)
 *   **Scenario:** You have 1 Petabyte of raw video in a warehouse. Your cluster is 3,000 miles away.
-*   **Crisis:** Project deadline is in 10 days. 
+*   **Crisis:** Project deadline is in 10 days.
 *   **Task:** Calculate the transfer time over 1Gbps fiber. Realize it will take weeks. Toggle to "Snowball" (Sneakernet) and see the physical delivery time beat the fiber.
 
 ### Act II: The Feeding Tax (15m)