Add tool annotations and PR close/reopen support (#174)

Add MCP `ToolAnnotation` metadata (Title, ReadOnlyHint, DestructiveHint)
to all registered tools so MCP hosts (VS Code, Claude, Cursor) get
accurate per-tool hints. A shared `pkg/annotation` package exposes
`ReadOnly`, `Write`, and `Destructive` helpers for consistency.

Add `close` and `reopen` methods to `pull_request_write` so PR state
can be toggled without going through the generic `update` path.

Co-Authored-By: silverwind <me@silverwind.io>
Co-Authored-By: Claude (Opus 4.7) <noreply@anthropic.com>

operation/user/user.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 
+	"gitea.com/gitea/gitea-mcp/pkg/annotation"
 	"gitea.com/gitea/gitea-mcp/pkg/gitea"
 	"gitea.com/gitea/gitea-mcp/pkg/log"
 	"gitea.com/gitea/gitea-mcp/pkg/params"
@@ -36,6 +37,7 @@ var (
 	GetMyUserInfoTool = mcp.NewTool(
 		GetMyUserInfoToolName,
 		mcp.WithDescription("Get my user info"),
+		mcp.WithToolAnnotation(annotation.ReadOnly("Get current user information")),
 	)
 
 	// GetUserOrgsTool is the MCP tool for listing organizations for the authenticated user.
@@ -43,6 +45,7 @@ var (
 	GetUserOrgsTool = mcp.NewTool(
 		GetUserOrgsToolName,
 		mcp.WithDescription("Get organizations associated with the authenticated user"),
+		mcp.WithToolAnnotation(annotation.ReadOnly("Get user organizations")),
 		mcp.WithNumber("page", mcp.Description("page number"), mcp.DefaultNumber(defaultPage)),
 		mcp.WithNumber("perPage", mcp.Description("results per page (may be capped by the server's MAX_RESPONSE_ITEMS setting, default 50)"), mcp.DefaultNumber(defaultPageSize)),
 	)