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/ui/achievements/AchievementsScreen.kt

@@ -191,9 +191,7 @@ fun AchievementsScreen(
 
             else -> {
                 LazyColumn(
-                    modifier =
-                        Modifier
-                            .fillMaxSize(),
+                    modifier = Modifier.fillMaxSize(),
                     contentPadding = PaddingValues(start = 16.dp, end = 16.dp, bottom = 16.dp),
                     verticalArrangement = Arrangement.spacedBy(12.dp),
                 ) {