fix(tool): don't truncate auto tool name at hyphens in the module path

[Ricardo-M-L]

Problem

getFunctionName derives a tool's name from the Go function when WithName() isn't provided. To drop the -fm suffix that the runtime appends to method values, it does:

fullName := fnInfo.Name()
// Remove -fm suffix for method values
if dashIdx := strings.Index(fullName, "-"); dashIdx >= 0 {
    fullName = fullName[:dashIdx]
}

strings.Index finds the first hyphen. But runtime.FuncForPC(...).Name() returns the full module path, and module paths routinely contain hyphens — including this SDK's own module, github.com/MoonshotAI/kimi-agent-sdk/go. So the name is truncated at the first path hyphen and the function name is lost entirely.

Reproduced on main (function Search defined in package kimi):

getFunctionName(Search) -> "github_com/MoonshotAI/kimi"

The Search part is gone — any user whose module path contains a hyphen and who relies on auto-naming gets a wrong, collision-prone tool name.

Fix

Strip only the exact -fm suffix:

fullName = strings.TrimSuffix(fullName, "-fm")

For names without a path hyphen this is identical to the previous behavior (the -fm method-value suffix is the only - in such names). It just stops mangling names whose import path contains a hyphen.

Tests

• TestCreateTool_AutoNamePreservesFunctionName — the auto-derived name now ends with _Search instead of being truncated.
• TestGetFunctionName_StripsMethodValueSuffix — method values still have -fm stripped, with the path/name preserved.

Verification

$ go test ./...
ok  github.com/MoonshotAI/kimi-agent-sdk/go
ok  github.com/MoonshotAI/kimi-agent-sdk/go/wire
ok  github.com/MoonshotAI/kimi-agent-sdk/go/wire/jsonrpc2
ok  github.com/MoonshotAI/kimi-agent-sdk/go/wire/transport
ok  github.com/MoonshotAI/kimi-agent-sdk/go/test/e2e
ok  github.com/MoonshotAI/kimi-agent-sdk/go/test/integration

$ go vet ./...    # clean
$ gofmt -l go/tool.go go/tool_test.go    # clean