Move ZIL source and walkthrough to docs/

Move original ZIL source files (.zil, .xzap, .errors) and
walkthrough.md into docs/ to keep the project root clean.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/walkthrough.md

@@ -4,7 +4,7 @@
 
 You start in bed, in the dark, with a splitting headache.
 
-```
+```text
 turn on light
 get out of bed
 get gown
@@ -40,7 +40,7 @@ You arrive groggy. Ford gives you peanuts (+8 points). You have about 3 turns be
 
 Ford gives you the Guide and a towel around turn 6. You need to get the babel fish from the dispenser into your ear. This requires setting up a Rube Goldberg chain:
 
-```
+```text
 hang gown on hook
 put towel on drain
 put satchel in front of panel
@@ -56,7 +56,7 @@ The fish bounces off the gown, lands on the towel, a cleaning robot grabs it, cr
 
 Around turn 36, guards drag you to the Captain's Quarters. The Vogon Captain reads his poetry. With the babel fish you can understand it.
 
-```
+```text
 enjoy poetry
 ```
 
@@ -64,7 +64,7 @@ enjoy poetry
 
 After enjoying the poem, you can open the glass case in the Hold:
 
-```
+```text
 type on keyboard
 take plotter
 ```
@@ -85,7 +85,7 @@ You black out and enter the Dark room.
 
 You float in sensory deprivation. Wait a few turns, then use your senses to find the exit:
 
-```
+```text
 listen
 look
 walk
@@ -103,7 +103,7 @@ You wake aboard the stolen starship Heart of Gold. (+10 points on first entry)
 
 Go to the Engine Room (south from Aft Corridor). You'll need to argue your way in:
 
-```
+```text
 south
 south
 south
@@ -117,7 +117,7 @@ look
 
 On the third look, the spare Improbability Drive, pliers, and rasp appear. (+25 points)
 
-```
+```text
 take spare drive
 take pliers
 take rasp
@@ -130,7 +130,7 @@ north
 
 Go to the Pantry (west from Aft Corridor):
 
-```
+```text
 west
 talk to marvin
 talk to marvin
@@ -138,7 +138,7 @@ talk to marvin
 
 Marvin agrees to fix the jammed hatch mechanism. Wait 12 turns (or explore elsewhere), then go to the Access Space (east from Hatchway):
 
-```
+```text
 east
 east
 down
@@ -147,13 +147,13 @@ east
 
 Marvin is here and asks for a specific tool (randomly chosen — could be screwdriver, toothbrush, wrench, pliers, rasp, or tweezers). Give him whatever he asks for:
 
-```
+```text
 give [tool] to marvin
 ```
 
 (+25 points, hatch now opens)
 
-```
+```text
 west
 ```
 
@@ -163,7 +163,7 @@ west
 
 Go to the Galley (west from Fore Corridor):
 
-```
+```text
 up
 north
 west
@@ -172,7 +172,7 @@ push pad
 
 This starts the Nutrimatic processing tea. Wait through the countdown (it takes several turns). The Nutrimatic produces tea. **Be careful:** a missile countdown starts around turn 7-8. Take the tea before things go wrong:
 
-```
+```text
 take tea
 drink tea
 ```
@@ -185,19 +185,19 @@ drink tea
 
 You need both tea and the concept of "no tea" to impress the screening door. After drinking tea, you're back to holding "no tea" conceptually. Get another cup:
 
-```
+```text
 push pad
 ```
 
 Wait for tea, take it:
 
-```
+```text
 take tea
 ```
 
 Now go to the screening door (west exit from Aft Corridor):
 
-```
+```text
 east
 south
 south
@@ -213,7 +213,7 @@ The door, overwhelmed by the paradox, opens. (+25 points)
 
 You need the plotter (from the Vogon glass case) and the spare drive (from the Engine Room). Connect everything:
 
-```
+```text
 plug large plug into console
 plug small plug into plotter
 dip dangly bit in tea
@@ -232,7 +232,7 @@ A 24-turn countdown to landing begins.
 
 After 24 turns, the ship lands. Go to the Hatchway and down the ramp:
 
-```
+```text
 south
 down
 down
@@ -250,7 +250,7 @@ The game congratulates you and displays your final score.
 
 If you die in a dream and get dispatched to the Lair, you face the Ravenous Bugblatter Beast of Traal.
 
-```
+```text
 wear towel
 tell beast my name
 east
@@ -268,7 +268,7 @@ take interface
 ## Score Summary
 
 | Action                        | Points  |
-|--------|--------|
+| ----------------------------- | ------- |
 | Eat tablet                    | 10      |
 | Drink 3 beers                 | 15      |
 | Enter Vogon Hold              | 8       |
@@ -287,7 +287,7 @@ take interface
 ### Optional points
 
 | Action                        | Points  |
-|--------|--------|
+| ----------------------------- | ------- |
 | Defeat Beast (carve memorial) | 25      |
 | Take Nutrimatic interface     | 25      |
 | **Maximum possible**          | **420** |