feat(tools): add MCP tool annotations to all 66 tools

[basebandit]

Summary

Adds readOnlyHint, destructiveHint, idempotentHint, openWorldHint, and title annotations to every registered tool, per MCP spec 2025-03-26.

A small helper file (tools/annotations.go) defines four named annotation sets so each call site is one line:

Helper	When to use
readOnlyAnnotation	list / get / describe / status / history — no cluster mutation
destructiveAnnotation	delete / undo — destroys resources or rolls back state
creationAnnotation	create / load / restart — non-idempotent mutation
idempotentMutationAnnotation	update / scale / suspend / resume / pause / patch — desired-state mutation

openWorldHint is true for every tool because the Kubernetes API is an external system.

Coverage

66 tools across 11 files annotated. All existing tests pass without modification.

Stacked on

Based on chore/mcp-go-api-migration (#115). Merge order: #114 → #115 → this.

Test plan

• go build ./...
• go vet ./...
• go test -race ./...