fix(web): bundle deps into the server (noExternals) — kill the 47k-file install

The Windows installer ballooned to 154 MB and installed forever because the node-server
bundle externalized the WHOLE @unom/ui dependency tree (payload, lexical, date-fns,
prismjs…) to .output/server/node_modules — 47,567 files / 730 MB copied into Program
Files. Set Nitro `noExternals: true` so every dependency is bundled + tree-shaken into the
server output: .output drops to ~75 files / 10 MB, and the bare external imports
(srvx, seroval…) bun couldn't resolve at runtime are gone — so the console runs on bun
(no node, no node_modules), which is the issue we previously worked around with node.

Windows installer now ships bun.exe + the ~75-file .output (was node.exe + a node_modules
forest) and runs `bun .output\server\index.mjs`:
- windows-host.yml: fetch a pinned portable bun (build tool AND shipped runtime); drop the
  node fetch + the .output/server install; smoke-boot under the bundled bun.
- pack-host-installer.ps1 / punktfunk-host.iss: -NodeExe -> -BunExe; stage {app}\bun\bun.exe.
- web-run.cmd / build-web.ps1: run/restart on bun; docs updated.

Net win everywhere: the Linux .deb shrinks (node still runs the self-contained output), and
the docker web image — which already ran `bun run .output/server/index.mjs` with only
.output copied — is fixed (the externals had no node_modules to resolve at runtime).

Validated locally: noExternals build = 75 files / 10 MB; node AND bun both serve /login
(200) + static assets (200) + gate /api (401).

(A true single binary via `bun build --compile` is blocked for now: Nitro serves public
assets from an import.meta-relative path `--compile` doesn't embed (/$bunfs/public); the
75-file payload is the clean result.)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

scripts/windows/web-setup.ps1

@@ -1,6 +1,6 @@
 <#
   Provision the punktfunk web console after the host installer has laid down its payload
-  ({app}\web\.output, {app}\node\node.exe, {app}\web\web-run.cmd). Invoked elevated from the
+  ({app}\web\.output, {app}\bun\bun.exe, {app}\web\web-run.cmd). Invoked elevated from the
   installer's [Run] section; idempotent (safe to re-run on upgrade).
 
     1. Sets the console login password file %ProgramData%\punktfunk\web-password
@@ -71,7 +71,7 @@ $settings = New-ScheduledTaskSettingsSet -AllowStartIfOnBatteries -DontStopIfGoi
     -StartWhenAvailable -RestartInterval (New-TimeSpan -Minutes 1) -RestartCount 10 `
     -ExecutionTimeLimit (New-TimeSpan -Seconds 0)
 Register-ScheduledTask -TaskName $TaskName -Action $action -Trigger $trigger -Principal $principal `
-    -Settings $settings -Description 'punktfunk web management console (Nitro/Node SSR on :3000)' `
+    -Settings $settings -Description 'punktfunk web management console (Nitro SSR on bun, :3000)' `
     -Force | Out-Null
 Write-Host "registered scheduled task $TaskName -> $cmd"