[enhancement] feat(#606): support auth mode + bearer token when adding HTTP MCP servers (#607)

* feat(#606): support auth mode + bearer token when adding HTTP MCP servers

- Extend AddMcpServerRequest with auth (none|header|oauth) and bearerToken
- Add auth mode FilterChip selector in HTTP add-server dialog
- Conditionally show masked bearer token field when auth == header
- Wire new fields through McpServersViewModel request builder

Backend contract: exactly one of url/command required; bearer_token
requires auth == "header"; args/env only for stdio. SnakeCase naming
strategy auto-serializes bearerToken -> bearer_token.

Fixes #606

* fix(#606): address agy review — remember PasswordVisualTransformation + FlowRow for auth chips

- Wrap PasswordVisualTransformation in remember {} to avoid per-recomposition allocation
- Use FlowRow for the 3 auth-mode FilterChips so they wrap on narrow screens instead of overflowing

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

@@ -31,6 +31,8 @@ data class AddMcpServerRequest(
     val command: String? = null,
     val args: List<String>? = null,
     val env: Map<String, String>? = null,
+    val auth: String? = null, // "none" | "header" | "oauth"
+    val bearerToken: String? = null, // sent only when auth == "header"
 )
 
 @Serializable