feat: add searxng web-search provider, openrouter cost balance UI, offline scripts; update source-launch and docs

scripts/offline/install-deps.ps1

@@ -0,0 +1,69 @@
+# Install from caches filled by download-deps.ps1. Unpacks the official Node zip
+# into .offline-cache/node/runtime and prepends it to PATH so the offline machine
+# does not need a system Node. Fails if any lockfile package is missing from
+# .offline-store (no registry access).
+#
+# Usage (repo root):  powershell -File scripts/offline/install-deps.ps1 [-Build]
+[CmdletBinding()]
+param(
+  [switch]$Build
+)
+$ErrorActionPreference = 'Stop'
+Set-StrictMode -Version Latest
+
+$Root = (Resolve-Path (Join-Path $PSScriptRoot '..\..')).Path
+Set-Location $Root
+
+function Import-OfflineNode {
+  $nodeCache = Join-Path $Root '.offline-cache\node'
+  $metaPath = Join-Path $nodeCache 'runtime.json'
+  if (-not (Test-Path $metaPath)) {
+    throw "Missing $metaPath. Run scripts/offline/download-deps.ps1 on a networked machine first, then copy the checkout."
+  }
+  $meta = Get-Content $metaPath -Raw | ConvertFrom-Json
+  $archivePath = Join-Path $nodeCache ([string]$meta.archive)
+  $runtimeDir = Join-Path $nodeCache 'runtime'
+  $nodeHome = Join-Path $runtimeDir ("node-v{0}-{1}" -f $meta.version, $meta.platform)
+  if (-not (Test-Path (Join-Path $nodeHome 'node.exe'))) {
+    if (-not (Test-Path $archivePath)) {
+      throw "Missing Node archive $archivePath. Re-run download-deps.ps1."
+    }
+    if (Test-Path $runtimeDir) { Remove-Item -Recurse -Force $runtimeDir }
+    New-Item -ItemType Directory -Force -Path $runtimeDir | Out-Null
+    Expand-Archive -LiteralPath $archivePath -DestinationPath $runtimeDir
+  }
+  if (-not (Test-Path (Join-Path $nodeHome 'node.exe'))) {
+    throw "Unpacked Node is missing: $nodeHome\node.exe"
+  }
+  $env:PATH = "$nodeHome;$env:PATH"
+  return $nodeHome
+}
+
+$nodeHome = Import-OfflineNode
+$storeDir = Join-Path $Root '.offline-store'
+$corepackHome = Join-Path $Root '.offline-cache\corepack'
+if (-not (Test-Path $storeDir)) {
+  throw "Missing $storeDir. Run scripts/offline/download-deps.ps1 on a networked machine first, then copy the checkout."
+}
+if (-not (Test-Path $corepackHome)) {
+  throw "Missing $corepackHome. Re-run download-deps.ps1 so Corepack pnpm is cached in-repo."
+}
+
+$env:COREPACK_HOME = $corepackHome
+$env:COREPACK_ENABLE_NETWORK = '0'
+
+$manifest = Get-Content (Join-Path $Root 'package.json') -Raw | ConvertFrom-Json
+$packageManager = [string]$manifest.packageManager
+$corepack = Join-Path $nodeHome 'corepack.cmd'
+
+Write-Host "Offline install $packageManager from $storeDir (Node $(& (Join-Path $nodeHome 'node.exe') --version))"
+& $corepack pnpm install --offline --frozen-lockfile --store-dir $storeDir
+
+if ($Build) {
+  Write-Host 'Building host/client libs, then the web frontend'
+  npm run build:lib
+  & $corepack pnpm --dir apps/web run build
+  Write-Host "Build complete. Start the UI with: `"$nodeHome\corepack.cmd`" pnpm dsh web"
+} else {
+  Write-Host 'Install complete. For dsh web also run: powershell -File scripts/offline/install-deps.ps1 -Build'
+}