feat(auth): add PAT auth, scoped REST/MCP access, CSRF, and tenant isolation

Introduce Personal Access Tokens (nzp_*) as a stateless auth path alongside
JWT, gated per-endpoint by a scope middleware (nezha:{resource}:{verb}) with
fail-closed empty-scope defaults and a server-id whitelist. Self-management
endpoints (profile, api-tokens, oauth2 bind, refresh-token) explicitly reject
PATs to block privilege-escalation chains. A revoke registry tears down active
long-lived connections (terminal, fm, ws, transfer, mcp) the moment a PAT is
deleted, with a tombstone closing the revoke->register race.

Add an MCP endpoint that proxies tool calls (exec, fs read/write/delete,
transfer) to agents over gRPC, guarded by origin/DNS-rebinding checks, a
per-token rate limiter, audit logging, and a kill switch. Serialize all
sends through the IOStream wrapper to honour grpc-go's concurrency contract.

Add CSRF double-submit protection on unsafe cookie-authenticated methods,
exempting authenticated PAT requests by context identity (not a forgeable
Authorization header). Apply visibility/whitelist filtering consistently
across list, get-by-id, and mutate paths to enforce tenant isolation.

Migrate legacy mcp:* scopes: rewrite read/exec to nezha:* equivalents and
drop dangerous write/delete/wildcard grants.

Co-authored-by: cloudcode <cloudcode@users.noreply.github.com>

cmd/dashboard/controller/mcp_capability.go

@@ -0,0 +1,74 @@
+package controller
+
+import (
+	"strings"
+
+	"github.com/nezhahq/nezha/model"
+)
+
+// MCPMinAgentVersion 是支持 MCP 的最低 agent 版本。
+//
+// release 流程：在 agent ship 了 MCP handlers 后，把此值更新为该 release 的版本号。
+// 不变量：必须为非空。否则旧 agent 收到 TaskTypeExec/TaskTypeFs* 等新任务类型时
+// 走 default 分支不回 TaskResult，dashboard 要等 CallAgent 超时（30s）甚至更久
+// （fs.transfer 的 IOStream attach 30s）才能感知，这是 server-transfer 已经
+// 通过 MinServerTransferAgentVersion 修复过的同类问题。
+const MCPMinAgentVersion = "v2.1.0"
+
+// requireAgentSupportsMCP 在 tool handler 调 CallAgent 之前快速失败不支持的 agent。
+// 仅作为 UX 优化：真正的安全/正确性由 agent 端 task switch 的 default 分支保障。
+func requireAgentSupportsMCP(server *model.Server) error {
+	if MCPMinAgentVersion == "" || server == nil || server.Host == nil {
+		return nil
+	}
+	if compareSemver(server.Host.Version, MCPMinAgentVersion) < 0 {
+		return errMCPUnsupported
+	}
+	return nil
+}
+
+// compareSemver 比较两个 "MAJOR.MINOR.PATCH[-suffix]" 字符串。
+// 返回 -1/0/1。无法解析时按字符串字典序比较，保证全序但可能不精确——
+// 对于 "agent 太老" 的快速失败用途已经足够。
+func compareSemver(a, b string) int {
+	if a == b {
+		return 0
+	}
+	aparts := semverParts(a)
+	bparts := semverParts(b)
+	for i := 0; i < 3; i++ {
+		if aparts[i] < bparts[i] {
+			return -1
+		}
+		if aparts[i] > bparts[i] {
+			return 1
+		}
+	}
+	if a < b {
+		return -1
+	}
+	if a > b {
+		return 1
+	}
+	return 0
+}
+
+func semverParts(v string) [3]int {
+	v = strings.TrimPrefix(v, "v")
+	if i := strings.IndexAny(v, "-+"); i >= 0 {
+		v = v[:i]
+	}
+	var out [3]int
+	parts := strings.Split(v, ".")
+	for i := 0; i < 3 && i < len(parts); i++ {
+		n := 0
+		for _, c := range parts[i] {
+			if c < '0' || c > '9' {
+				break
+			}
+			n = n*10 + int(c-'0')
+		}
+		out[i] = n
+	}
+	return out
+}