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/zai.json

@@ -0,0 +1,22 @@
+{
+  "provider": "zai",
+  "description": "Z.AI GLM coding plan. Same endpoint the official coding helper uses, but with real per-tier model mapping.",
+  "baseUrl": "https://api.z.ai/api/anthropic",
+  "auth": {
+    "mode": "vault",
+    "keyRef": "zai"
+  },
+  "models": {
+    "opus": "glm-5.2",
+    "sonnet": "glm-5.2",
+    "haiku": "glm-4.7",
+    "fable": "glm-5.2"
+  },
+  "subagentModel": "inherit",
+  "gatewayModelDiscovery": false,
+  "extraEnv": {
+    "API_TIMEOUT_MS": "3000000",
+    "CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC": "1"
+  },
+  "contextTokens": 1000000
+}