feat: richer Webhooks tab — create, toggle, delete subscriptions (#454)

* feat: richer Webhooks tab — create, toggle, delete subscriptions

Adds full webhook subscription management matching the dashboard UI:
- Create subscription dialog (name, description, events, deliver, secret)
- Per-subscription enable/disable toggle via PUT endpoint
- Delete with confirmation dialog
- Enhanced subscription cards: description, event chips, delivery badge,
  secret indicator, URL display
- Search filtering across name, description, and events
- Updated Webhook.kt model with full API shape
- New HermesApiService endpoints for CRUD operations

Closes #447

* fix: remove double top padding on webhooks screen LazyColumn

* fix: use string resources in webhooks screen (sweep hardcoded strings)

* fix: resolve unresolved merge conflict in AchievementsScreen

Leftover <<<<<<< markers from a main merge broke compilation on the
webhooks-full-parity branch, cascading through ktlint/lint/tests.

---------

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

app/src/main/java/com/m57/hermescontrol/data/model/Webhook.kt

@@ -8,10 +8,38 @@ data class WebhooksResponse(
 
 data class WebhookSubscription(
     val name: String,
-    val url: String,
+    val description: String?,
     val events: List<String>?,
+    val deliver: String?,
+    val deliver_only: Boolean?,
+    val prompt: String?,
+    val skills: List<String>?,
+    val created_at: String?,
+    val url: String,
+    val secret_set: Boolean?,
+    val enabled: Boolean?,
+)
+
+data class CreateWebhookRequest(
+    val name: String,
+    val description: String? = null,
+    val events: List<String>? = null,
+    val prompt: String? = null,
+    val skills: List<String>? = null,
+    val deliver: String? = null,
+    val deliver_only: Boolean? = null,
+    val deliver_chat_id: String? = null,
+    val secret: String? = null,
 )
 
 data class WebhooksToggleRequest(
     val enabled: Boolean,
 )
+
+data class WebhookToggleSubscriptionRequest(
+    val enabled: Boolean,
+)
+
+data class DeleteWebhookResponse(
+    val ok: Boolean,
+)