feat(#444): MCP tab parity — add servers, catalog, env vars, restart, diagnostics (#462)

* feat(#444): add MCP API endpoints and data models

- Add McpServer.status and McpServer.error fields for diagnostics
- Add AddMcpServerRequest, McpCatalogResponse/Entry/EnvVar models
- Add McpServerTestResponse model
- Add POST addMcpServer, PUT updateMcpServer, POST restartMcpServer
- Add GET getMcpCatalog, POST installMcpCatalogEntry

* feat(#444): add server form, enriched server cards, catalog section

- Add HTTP/stdio inline server form with tabs
- Enriched server cards with status badge, restart, env var editing
- Add/edit/remove environment variables per server
- Catalog section with search, result cards, install flow with env vars
- Status badge colors: running=green, error=red, stopped/gray
- Server diagnostics shown as error badges on cards
- New string resources for all MCP UI elements

* fix(#444): add missing McpServer import to HermesApiService

* fix(#444): cleanup review issues — dead code, spinner, unused strings

- Remove unused serverDiagnostics from UiState
- Remove unused showDiagnostics local state in ServerCard
- Remove unused McpServerTestResponse model
- Remove redundant refreshDiagnostics() alias
- Replace catalog loading text with CircularProgressIndicator
- Remove unused string resources (action_restarting, diagnostics, catalog_load)

* fix(#444): remove remaining showDiagnostics reference at line 348

---------

Co-authored-by: Hermes Agent <hermes@agent.local>

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

@@ -12,8 +12,44 @@ data class McpServer(
     val args: List<String>?,
     val env: Map<String, String>?,
     val enabled: Boolean,
+    val status: String? = null,
+    val error: String? = null,
 )
 
 data class McpServerToggleRequest(
     val enabled: Boolean,
 )
+
+data class AddMcpServerRequest(
+    val name: String,
+    val url: String? = null,
+    val command: String? = null,
+    val args: List<String>? = null,
+    val env: Map<String, String>? = null,
+)
+
+data class McpCatalogResponse(
+    val entries: List<McpCatalogEntry>,
+)
+
+data class McpCatalogEntry(
+    val name: String,
+    val description: String? = null,
+    val source: String? = null,
+    val url: String? = null,
+    val command: String? = null,
+    val args: List<String>? = null,
+    val env: List<McpCatalogEnvVar>? = null,
+)
+
+data class McpCatalogEnvVar(
+    val key: String,
+    val label: String? = null,
+    val description: String? = null,
+    val required: Boolean = false,
+)
+
+data class McpCatalogInstallRequest(
+    val name: String,
+    val env: Map<String, String>? = null,
+)