Initial commit: full Phases 1-6 implementation

Post-repair hardware validation pipeline for Proxmox cluster hosts.
Go orchestrator + in-image agent + mkosi live image + bundled dnsmasq
PXE + SQLite + HTMX/SSE UI + notify registry + janitor + full docs.

internal/web/templates/login.templ

@@ -0,0 +1,20 @@
+package templates
+
+templ Login(errMsg, next string) {
+	@BareLayout("Sign in") {
+		<div class="login-card">
+			<h1>Vetting</h1>
+			if errMsg != "" {
+				<div class="error">{ errMsg }</div>
+			}
+			<form method="post" action="/login">
+				<input type="hidden" name="next" value={ next }/>
+				<label>
+					Password
+					<input type="password" name="password" autofocus required/>
+				</label>
+				<button type="submit">Sign in</button>
+			</form>
+		</div>
+	}
+}