Add missing tool parameters from Gitea SDK

Expose additional parameters that the Gitea SDK supports but were not
yet wired through the MCP tool definitions:

- list_issues: labels, since, before filters
- issue_write: labels and deadline on create, deadline/remove_deadline on update
- pull_request_write: labels/deadline on create/update, remove_deadline on update,
  force_merge/merge_when_checks_succeed/head_commit_id on merge
- list_branches: page/perPage pagination
- create_repo: trust_model, object_format_name
- label_write: is_archived on create/edit

Also adds params.GetOptionalTime helper for RFC3339 timestamp parsing
and tests for the most important new parameters.

Co-Authored-By: Claude (claude-opus-4-6) <noreply@anthropic.com>

operation/label/label.go

@@ -47,6 +47,7 @@ var (
 		mcp.WithString("color", mcp.Description("label color hex code e.g. #RRGGBB (required for create, optional for edit)")),
 		mcp.WithString("description", mcp.Description("label description")),
 		mcp.WithBoolean("exclusive", mcp.Description("whether the label is exclusive (org labels only)")),
+		mcp.WithBoolean("is_archived", mcp.Description("whether the label is archived (for create/edit repo label methods)")),
 	)
 )
 
@@ -178,10 +179,13 @@ func createRepoLabelFn(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallT
 	}
 	description, _ := req.GetArguments()["description"].(string) // Optional
 
+	isArchived, _ := req.GetArguments()["is_archived"].(bool)
+
 	opt := gitea_sdk.CreateLabelOption{
 		Name:        name,
 		Color:       color,
 		Description: description,
+		IsArchived:  isArchived,
 	}
 
 	client, err := gitea.ClientFromContext(ctx)
@@ -220,6 +224,9 @@ func editRepoLabelFn(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToo
 	if description, ok := req.GetArguments()["description"].(string); ok {
 		opt.Description = new(description)
 	}
+	if isArchived, ok := req.GetArguments()["is_archived"].(bool); ok {
+		opt.IsArchived = &isArchived
+	}
 
 	client, err := gitea.ClientFromContext(ctx)
 	if err != nil {