feat(collect): remove power-on/off, add skip-hung for Redfish collection

Remove power-on and power-off functionality from the Redfish collector;
keep host power-state detection and show a warning in the UI when the
host is powered off before collection starts.

Add a "Пропустить зависшие" (skip hung) button that lets the user abort
stuck Redfish collection phases without losing already-collected data.
Introduces a two-level context model in Collect(): the outer job context
covers the full lifecycle including replay; an inner collectCtx covers
snapshot, prefetch, and plan-B phases only. Closing the skipCh cancels
collectCtx immediately — aborts all in-flight HTTP requests and exits
plan-B loops — then replay runs on whatever rawTree was collected.

Signal path: UI → POST /api/collect/{id}/skip → JobManager.SkipJob()
→ close(skipCh) → goroutine in Collect() → cancelCollect().

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/static/css/style.css

@@ -211,8 +211,6 @@ main {
 }
 
 #api-connect-btn,
-#api-power-on-collect-btn,
-#api-collect-off-btn,
 #convert-folder-btn,
 #convert-run-btn,
 #cancel-job-btn,
@@ -229,8 +227,6 @@ main {
 }
 
 #api-connect-btn:hover,
-#api-power-on-collect-btn:hover,
-#api-collect-off-btn:hover,
 #convert-folder-btn:hover,
 #convert-run-btn:hover,
 #cancel-job-btn:hover,
@@ -241,8 +237,6 @@ main {
 #convert-run-btn:disabled,
 #convert-folder-btn:disabled,
 #api-connect-btn:disabled,
-#api-power-on-collect-btn:disabled,
-#api-collect-off-btn:disabled,
 #cancel-job-btn:disabled,
 .upload-area button:disabled {
     opacity: 0.6;
@@ -311,64 +305,19 @@ main {
     border-top: 1px solid #e2e8f0;
 }
 
-.api-confirm-modal-backdrop {
-    position: fixed;
-    inset: 0;
-    background: rgba(0, 0, 0, 0.45);
+.api-host-off-warning {
     display: flex;
     align-items: center;
-    justify-content: center;
-    z-index: 1000;
-}
-
-.api-confirm-modal {
-    background: #fff;
-    border-radius: 10px;
-    padding: 1.5rem 1.75rem;
-    max-width: 380px;
-    width: 90%;
-    box-shadow: 0 8px 32px rgba(0,0,0,0.18);
-}
-
-.api-confirm-modal p {
-    margin-bottom: 1.1rem;
-    font-size: 0.95rem;
-    color: #333;
-    line-height: 1.5;
-}
-
-.api-confirm-modal-actions {
-    display: flex;
-    gap: 0.6rem;
-    justify-content: flex-end;
-}
-
-.api-confirm-modal-actions button {
-    border: none;
+    gap: 0.4rem;
+    padding: 0.5rem 0.75rem;
+    background: #fef3c7;
+    border: 1px solid #f59e0b;
     border-radius: 6px;
-    padding: 0.5rem 1rem;
-    font-size: 0.9rem;
-    font-weight: 600;
-    cursor: pointer;
+    font-size: 0.875rem;
+    color: #92400e;
+    font-weight: 500;
 }
 
-.api-confirm-modal-actions .btn-cancel {
-    background: #e2e8f0;
-    color: #333;
-}
-
-.api-confirm-modal-actions .btn-cancel:hover {
-    background: #cbd5e1;
-}
-
-.api-confirm-modal-actions .btn-confirm {
-    background: #dc3545;
-    color: #fff;
-}
-
-.api-confirm-modal-actions .btn-confirm:hover {
-    background: #b02a37;
-}
 
 .api-connect-status {
     margin-top: 0.75rem;
@@ -445,6 +394,33 @@ main {
     cursor: default;
 }
 
+.job-status-actions {
+    display: flex;
+    gap: 0.5rem;
+    align-items: center;
+}
+
+#skip-hung-btn {
+    background: #f59e0b;
+    color: #fff;
+    border: none;
+    border-radius: 6px;
+    padding: 0.5rem 0.9rem;
+    font-size: 0.875rem;
+    font-weight: 600;
+    cursor: pointer;
+    transition: background-color 0.2s ease, opacity 0.2s ease;
+}
+
+#skip-hung-btn:hover {
+    background: #d97706;
+}
+
+#skip-hung-btn:disabled {
+    opacity: 0.6;
+    cursor: not-allowed;
+}
+
 .job-status-meta {
     display: grid;
     grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));