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.

profile-snippet.ps1

@@ -0,0 +1,51 @@
+# >>> claude-mode >>>
+# Installed by claude-code-switcher. Do not edit between the markers;
+# re-run install.ps1 instead.
+
+function claude-mode {
+    & (Join-Path $env:USERPROFILE '.claude-mode\claude-mode.ps1') @args
+}
+
+# Wrapper around claude.exe. settings.json is the single source of truth for
+# gateway config, so any inherited process-level copy of these variables is
+# stripped before launch: a stale ANTHROPIC_API_KEY would silently bypass the
+# OpenRouter gateway, and stale ANTHROPIC_BASE_URL / *_MODEL values would break
+# native Anthropic auth. Restored afterwards so other tools in the shell are
+# unaffected.
+function claude {
+    $exe = Get-Command 'claude.exe' -CommandType Application -ErrorAction SilentlyContinue | Select-Object -First 1
+    if (-not $exe) { Write-Error 'claude.exe not found on PATH'; return }
+
+    $names = @(
+        'ANTHROPIC_API_KEY',
+        'ANTHROPIC_AUTH_TOKEN',
+        'ANTHROPIC_BASE_URL',
+        'ANTHROPIC_DEFAULT_OPUS_MODEL',
+        'ANTHROPIC_DEFAULT_SONNET_MODEL',
+        'ANTHROPIC_DEFAULT_HAIKU_MODEL',
+        'ANTHROPIC_DEFAULT_FABLE_MODEL',
+        'CLAUDE_CODE_SUBAGENT_MODEL',
+        'CLAUDE_CODE_ENABLE_GATEWAY_MODEL_DISCOVERY',
+        'CLAUDE_CODE_ATTRIBUTION_HEADER',
+        'CLAUDE_CODE_AUTO_COMPACT_WINDOW',
+        'CLAUDE_CODE_MAX_CONTEXT_TOKENS',
+        'CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC',
+        'API_TIMEOUT_MS'
+    )
+
+    $saved = @{}
+    foreach ($n in $names) {
+        $v = [Environment]::GetEnvironmentVariable($n, 'Process')
+        if ($null -ne $v) {
+            $saved[$n] = $v
+            [Environment]::SetEnvironmentVariable($n, $null, 'Process')
+        }
+    }
+
+    try {
+        & $exe.Source @args
+    } finally {
+        foreach ($n in $saved.Keys) { [Environment]::SetEnvironmentVariable($n, $saved[$n], 'Process') }
+    }
+}
+# <<< claude-mode <<<