docs: add AfterCoin documentation and MetaMask guides

Comprehensive docs covering architecture, all components, Docker
services, environment variables, MetaMask connection (desktop + mobile),
administration commands, and troubleshooting.

Also adds Lua scripts to repo for version control, including the
periodic chain sync loop (every 30s) in the mainframe.

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

servers/minecraft/lua-scripts/mainframe_startup.lua

@@ -0,0 +1,164 @@
+rednet.open("left")
+local databasePath = "players"
+local database
+
+-- AfterCoin Bridge config
+local BRIDGE_URL = "http://afc-bridge:3001"
+local BRIDGE_SECRET = "afterlife_bridge_dev_2024"
+local SYNC_INTERVAL = 30 -- seconds between chain sync polls
+
+-- HTTP helper: POST to bridge API
+local function bridgePost(endpoint, body)
+	local url = BRIDGE_URL .. endpoint
+	local jsonBody = textutils.serialiseJSON(body)
+	local ok, result = pcall(function()
+		local response, failReason = http.post(url, jsonBody, {
+			["Content-Type"] = "application/json",
+			["x-bridge-secret"] = BRIDGE_SECRET
+		})
+		if not response then
+			print("[Bridge] POST failed: " .. tostring(failReason))
+			return nil
+		end
+		local data = textutils.unserialiseJSON(response.readAll())
+		response.close()
+		return data
+	end)
+	if not ok then
+		print("[Bridge] POST error: " .. tostring(result))
+		return nil
+	end
+	return result
+end
+
+-- HTTP helper: GET from bridge API
+local function bridgeGet(endpoint)
+	local url = BRIDGE_URL .. endpoint
+	local ok, result = pcall(function()
+		local response, failReason = http.get(url)
+		if not response then
+			print("[Bridge] GET failed: " .. tostring(failReason))
+			return nil
+		end
+		local data = textutils.unserialiseJSON(response.readAll())
+		response.close()
+		return data
+	end)
+	if not ok then
+		print("[Bridge] GET error: " .. tostring(result))
+		return nil
+	end
+	return result
+end
+
+-- Sync on-chain balance for a player (returns on-chain balance or nil)
+local function syncFromChain(diskId)
+	local resp = bridgeGet("/api/balance/" .. tostring(diskId))
+	if resp and resp.success then
+		return resp.balance
+	end
+	return nil
+end
+
+-- Save database to disk
+local function saveDatabase()
+	local file = fs.open(databasePath, "w")
+	file.write(textutils.serialise(database))
+	file.close()
+end
+
+if not fs.exists(databasePath) then
+	database = {}
+	local file, err = fs.open(databasePath, "w")
+	if not file then
+		print("ERROR creating db: "..tostring(err))
+		print("Trying alternate path...")
+		databasePath = "/players.txt"
+		file, err = fs.open(databasePath, "w")
+		if not file then
+			print("FATAL: "..tostring(err))
+			return
+		end
+	end
+	file.write("{}")
+	file.close()
+else
+	local file = fs.open(databasePath, "r")
+	database = textutils.unserialise(file.readAll())
+	file.close()
+end
+
+print("Database loaded.")
+print("AfterCoin bridge: " .. BRIDGE_URL)
+
+-- Rednet message handler
+local function messageLoop()
+	while true do
+		local id, data = rednet.receive("otto")
+		print(textutils.serialise(data))
+		if data.type == "getPlayerBalance" then
+			print("Fetching balance for ", data.player)
+			local chainBalance = syncFromChain(data.player)
+			if chainBalance and database[data.player] then
+				database[data.player].balance = chainBalance
+			end
+			rednet.send(id, database[data.player], "otto")
+		elseif data.type == "setPlayerBalance" then
+			print("Setting balance for ", data.player, " to ", data.balance)
+			local oldBalance = database[data.player].balance
+			local diff = data.balance - oldBalance
+			database[data.player].balance = data.balance
+			saveDatabase()
+			if diff > 0 then
+				print("[Bridge] Minting " .. diff .. " AFC")
+				bridgePost("/api/deposit", {diskId=tostring(data.player), amount=diff})
+			elseif diff < 0 then
+				print("[Bridge] Burning " .. math.abs(diff) .. " AFC")
+				bridgePost("/api/withdraw", {diskId=tostring(data.player), amount=math.abs(diff)})
+			end
+			rednet.send(id, nil, "otto")
+		elseif data.type == "addPlayer" then
+			print("Adding player: #"..data.player, data.name)
+			database[data.player] = {
+				name=data.name,
+				balance=0
+			}
+			saveDatabase()
+			print("[Bridge] Registering wallet for " .. data.name)
+			bridgePost("/api/register", {diskId=tostring(data.player), name=data.name})
+			rednet.send(id, nil, "otto")
+		elseif data.type == "getLeaderboard" then
+			print("Sending leaderboard")
+			local leaderboard = {}
+			for pid, pdata in pairs(database) do
+				table.insert(leaderboard, {name=pdata.name, balance=pdata.balance})
+			end
+			table.sort(leaderboard, function(a, b) return a.balance > b.balance end)
+			rednet.send(id, leaderboard, "otto")
+		end
+	end
+end
+
+-- Periodic chain sync loop
+local function syncLoop()
+	while true do
+		os.sleep(SYNC_INTERVAL)
+		local changed = false
+		for pid, pdata in pairs(database) do
+			local chainBalance = syncFromChain(pid)
+			if chainBalance and chainBalance ~= pdata.balance then
+				print("[Sync] " .. pdata.name .. ": " .. pdata.balance .. " -> " .. chainBalance .. " AFC")
+				database[pid].balance = chainBalance
+				changed = true
+			end
+		end
+		if changed then
+			saveDatabase()
+			print("[Sync] Database updated from chain.")
+		end
+	end
+end
+
+-- Run both loops in parallel
+print("Starting message handler + chain sync (every " .. SYNC_INTERVAL .. "s)...")
+parallel.waitForAll(messageLoop, syncLoop)