M0: skelett, byggkedja och dokumentation för JP Subway Pussel

- Go 1.27 + Ebitengine v2.10, intern upplösning 320x180 med heltalsskalning
- internal/res (resursuppslag), internal/rng (seedad slump), internal/level
  (banformat, validering, BFS-lösbarhet) med tester; internal/archtest
  kontrollerar att bara presentationslagret beror på Ebitengine
- tools/build: debug -> build/debug/, release -> build/release/<os>-<arch>/
  med resources/ bredvid binären; Windows korsbyggs utan C-verktyg
- VS Code tasks (build/test/release) och launch (dlv)
- Första banan 001-flygplatsen, sv/en-texter, skyltordbok, placeholder-sprite
- doc/: spelbeskrivning (renskriven), mål och tester, roadmap med teknikval
  (M0–M12), plan.md; README med bygg- och beroendeinformation

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

.vscode/tasks.json

@@ -0,0 +1,81 @@
+{
+  // Byggtasks. Allt går via `go run ./tools/build` så att samma kommandon
+  // fungerar på Linux och Windows utan make/bash.
+  // Ctrl+Shift+B = "build" (debug). Terminal > Run Task… för övriga.
+  "version": "2.0.0",
+  "tasks": [
+    {
+      "label": "build",
+      "detail": "Debug-bygge → build/debug/ (standard, Ctrl+Shift+B)",
+      "type": "process",
+      "command": "go",
+      "args": ["run", "./tools/build", "-mode", "debug"],
+      "group": { "kind": "build", "isDefault": true },
+      "problemMatcher": ["$go"],
+      "presentation": { "reveal": "silent", "clear": true }
+    },
+    {
+      "label": "build: release (linux-amd64)",
+      "detail": "Release-bygge → build/release/linux-amd64/",
+      "type": "process",
+      "command": "go",
+      "args": ["run", "./tools/build", "-mode", "release", "-os", "linux", "-arch", "amd64"],
+      "group": "build",
+      "problemMatcher": ["$go"],
+      "presentation": { "clear": true }
+    },
+    {
+      "label": "build: release (windows-amd64)",
+      "detail": "Release-bygge (korsbygge, ren Go) → build/release/windows-amd64/",
+      "type": "process",
+      "command": "go",
+      "args": ["run", "./tools/build", "-mode", "release", "-os", "windows", "-arch", "amd64"],
+      "group": "build",
+      "problemMatcher": ["$go"],
+      "presentation": { "clear": true }
+    },
+    {
+      "label": "build: release (alla plattformar)",
+      "detail": "Linux + Windows release-byggen",
+      "dependsOn": ["build: release (linux-amd64)", "build: release (windows-amd64)"],
+      "dependsOrder": "sequence",
+      "group": "build",
+      "problemMatcher": []
+    },
+    {
+      "label": "run: debug",
+      "detail": "Bygg debug och starta spelet (utan debugger)",
+      "type": "process",
+      "command": "go",
+      "args": ["run", "./tools/build", "-mode", "debug", "-run"],
+      "problemMatcher": ["$go"],
+      "presentation": { "clear": true }
+    },
+    {
+      "label": "test",
+      "detail": "go test ./...",
+      "type": "process",
+      "command": "go",
+      "args": ["test", "./..."],
+      "group": { "kind": "test", "isDefault": true },
+      "problemMatcher": ["$go"],
+      "presentation": { "clear": true }
+    },
+    {
+      "label": "test: verbose med race-detektor",
+      "type": "process",
+      "command": "go",
+      "args": ["test", "-race", "-v", "./..."],
+      "group": "test",
+      "problemMatcher": ["$go"],
+      "presentation": { "clear": true }
+    },
+    {
+      "label": "vet",
+      "type": "process",
+      "command": "go",
+      "args": ["vet", "./..."],
+      "problemMatcher": ["$go"]
+    }
+  ]
+}