Import claude-code-switcher from the Windows build

Source of truth so far has been c:\Users\smoido\projects\cli on the Windows
box, which has no git history of its own. This is that tree copied verbatim over
SSH, minus dist/ - the PowerShell build, the POSIX port under linux/, and the
presets both share.

Recorded as its own commit so that everything after it is a reviewable diff
rather than an undifferentiated first drop.

presets/cheap.json

@@ -0,0 +1,18 @@
+{
+  "provider": "openrouter",
+  "description": "Minimum cost. Everything on flash-class models with 1M context.",
+  "baseUrl": "https://openrouter.ai/api",
+  "auth": {
+    "mode": "vault",
+    "keyRef": "openrouter"
+  },
+  "models": {
+    "opus": "deepseek/deepseek-v4-pro",
+    "sonnet": "deepseek/deepseek-v4-flash-0731",
+    "haiku": "qwen/qwen3.7-flash",
+    "fable": "openai/gpt-5.6-luna-pro"
+  },
+  "subagentModel": "qwen/qwen3.7-flash",
+  "gatewayModelDiscovery": true,
+  "contextTokens": 1000000
+}