Phase 3: embed web UI with go:embed, pinned TypeScript toolchain, drop i18n, add /healthz

- html/embed.go embeds html/ (pages, css, img, js, video); src/assets.go
  serves it, with os.DirFS("html") under -dev. Static assets get an ETag
  and Cache-Control: no-cache; HTML pages are still templated (only the
  login error message is substituted now).
- Delete the generated src/webUI.go (783 KB base64), src/html-build.go and
  cmd/webui-gen; Dockerfile no longer runs a generator.
- Language layer removed: 254 {{.x}} placeholders inlined as English
  strings in ts/*.ts and the two auth pages; html/lang/en.json, the
  LanguageUI struct and the 'language' setting are gone.
- ts/tsconfig.json + package.json pin typescript 5.9.3; the seven sources
  compile (ES2020, global scripts) into one committed html/js/app.js.
  Ten unreferenced legacy scripts under html/js/ deleted; all pages load
  js/app.js.
- Fix the six type errors that blocked a clean compile, including a real
  bug: a missing semicolon in the search shortcut handler made the code
  call the result of preventDefault(), so the shortcut threw instead of
  focusing the search box.
- /healthz liveness endpoint; Dockerfile healthcheck and README use it.
- Drone: go vet, and a webui-check step that rebuilds the bundle and fails
  if the committed app.js is stale.
- README-DEV.md documents build, UI toolchain, -dev, versioning, CI.

ts/configuration_ts.ts

@@ -43,7 +43,7 @@ class WizardItem extends WizardCategory {
         select.id = key
         doc.appendChild(select)
 
-        description = "{{.wizard.tuner.description}}"
+        description = "Number of parallel connections that can be established to the provider.<br>Available for: Plex, Emby (HDHR), M3U (with active buffer).<br>After a change, xTeVe must be delete in the Plex / Emby DVR settings and set up again."
 
         break;
       
@@ -56,29 +56,29 @@ class WizardItem extends WizardCategory {
         select.id = key
         doc.appendChild(select)
 
-        description = "{{.wizard.epgSource.description}}"
+        description = "PMS:<br>- Use EPG data from Plex or Emby <br><br>XEPG:<br>- Use of one or more XMLTV files<br>- Channel management<br>- M3U / XMLTV export (HTTP link for IPTV apps)"
 
         break
 
       case "m3u":
         var input = content.createInput("text", key, "")
-        input.setAttribute("placeholder", "{{.wizard.m3u.placeholder}}")
+        input.setAttribute("placeholder", "File path or URL of the M3U")
         input.setAttribute("class", "wizard")
         input.id = key
         doc.appendChild(input)
 
-        description = "{{.wizard.m3u.description}}"
+        description = "Local or remote playlists"
 
         break
 
       case "xmltv":
         var input = content.createInput("text", key, "")
-        input.setAttribute("placeholder", "{{.wizard.xmltv.placeholder}}")
+        input.setAttribute("placeholder", "File path or URL of the XMLTV")
         input.setAttribute("class", "wizard")
         input.id = key
         doc.appendChild(input)
 
-        description = "{{.wizard.xmltv.description}}"
+        description = "Local or remote XMLTV file"
 
       break
 
@@ -143,7 +143,7 @@ function saveWizard() {
             value = (config[i] as HTMLInputElement).value
 
             if (value.length == 0) {
-              var msg = name.toUpperCase() + ": " + "{{.alert.missingInput}}"
+              var msg = name.toUpperCase() + ": " + "Missing input"
               alert(msg)
               return
             }
@@ -171,7 +171,7 @@ function saveWizard() {
 
 // Wizard
 var configurationWizard = new Array()
-configurationWizard.push(new WizardItem("tuner", "{{.wizard.tuner.title}}"))
-configurationWizard.push(new WizardItem("epgSource", "{{.wizard.epgSource.title}}"))
-configurationWizard.push(new WizardItem("m3u", "{{.wizard.m3u.title}}"))
-configurationWizard.push(new WizardItem("xmltv", "{{.wizard.xmltv.title}}"))
+configurationWizard.push(new WizardItem("tuner", "Number of tuners"))
+configurationWizard.push(new WizardItem("epgSource", "EPG Source"))
+configurationWizard.push(new WizardItem("m3u", "M3U Playlist"))
+configurationWizard.push(new WizardItem("xmltv", "XMLTV File"))