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/registration.templ

@@ -0,0 +1,61 @@
+package templates
+
+type RegistrationForm struct {
+	Name             string
+	MAC              string
+	WoLBroadcastIP   string
+	WoLPort          string
+	ExpectedSpecYAML string
+	Notes            string
+	Error            string
+}
+
+templ Registration(form RegistrationForm) {
+	@Layout("Register host") {
+		<section class="form-wrap">
+			<h1>Register host</h1>
+			if form.Error != "" {
+				<div class="error">{ form.Error }</div>
+			}
+			<form method="post" action="/hosts" class="host-form">
+				<label>
+					Name
+					<input type="text" name="name" value={ form.Name } required pattern="[A-Za-z0-9_\-\.]+" placeholder="pve-node-03"/>
+				</label>
+				<label>
+					MAC address
+					<input type="text" name="mac" value={ form.MAC } required placeholder="aa:bb:cc:dd:ee:ff"/>
+				</label>
+				<div class="grid-2">
+					<label>
+						WoL broadcast IP
+						<input type="text" name="wol_broadcast_ip" value={ form.WoLBroadcastIP } required placeholder="10.0.0.255"/>
+					</label>
+					<label>
+						WoL port
+						<input type="number" name="wol_port" value={ defaultPort(form.WoLPort) } min="1" max="65535"/>
+					</label>
+				</div>
+				<label>
+					Expected hardware spec (YAML)
+					<textarea name="expected_spec_yaml" rows="12" required placeholder="cpu:&#10;  model_match: ...">{ form.ExpectedSpecYAML }</textarea>
+				</label>
+				<label>
+					Notes
+					<textarea name="notes" rows="3">{ form.Notes }</textarea>
+				</label>
+				<div class="actions">
+					<button type="submit">Register</button>
+					<a class="button-secondary" href="/">Cancel</a>
+				</div>
+			</form>
+		</section>
+	}
+}
+
+func defaultPort(v string) string {
+	if v == "" {
+		return "9"
+	}
+	return v
+}