fix: let get_me handle missing arguments

[he-yufeng]

Fixes #2587.

Summary

get_me is a zero-argument tool, but it was registered through the generic argument-decoding helper. That still makes the call sensitive to whether a client sends {} or omits arguments entirely.

This patch registers get_me with the no-argument handler path instead. The handler does not need parsed arguments, so it can serve both forms consistently:

• arguments: {}
• no arguments field

Validation

• go test ./pkg/github -run Test_GetMe -count=1
• go test ./pkg/github -count=1
• go test ./... -count=1
• gofmt -w pkg/github/context_tools.go pkg/github/context_tools_test.go
• git diff --check origin/main..HEAD

[he-yufeng]

Updated this branch onto current origin/main.

Validated locally:

go test ./pkg/github -run Test_GetMe
go test ./pkg/github
git diff --check

[he-yufeng]

Rebased this branch on the latest upstream origin/main and reran validation locally.

Validated:

go test ./pkg/github -run Test_GetMe
go test ./pkg/github
go test ./...
git diff --check origin/main..HEAD

All passed.

[he-yufeng]

Re-ran validation on the current branch:\n\n- \go test ./pkg/github -run Test_GetMe -count=1\n- \go test ./pkg/github -count=1\n- \go test ./...\n- \git diff --check origin/main...HEAD\n\nAll passed locally on Windows.

[he-yufeng]

Rebased this branch onto the latest upstream main and force-pushed the cleaned head.

Validated locally:

• go test ./pkg/github -run Test_GetMe -count=1
• go test ./pkg/github -count=1
• go test ./...
• git diff --check origin/main..HEAD

[he-yufeng]

Rebased this branch onto current upstream main again; the PR remains a one-commit, two-file change.

Validation on Windows:

go test ./pkg/github -run Test_GetMe -count=1
go test ./pkg/github -count=1
go test ./...
git diff --check origin/main..HEAD

All passed.

[he-yufeng]

Rebased the approved branch onto current upstream main and resolved the conflict by keeping the newer attachStaticIFCLabel path while preserving the missing-arguments handling for get_me.

Validation on Windows:

• go test ./pkg/github -run Test_GetMe -count=1
• go test ./pkg/github -count=1
• go test ./...
• git diff --check origin/main..HEAD