* Add workload identity federation support to base-action

Move the workload identity module into base-action so the standalone
action can fetch and refresh the GitHub OIDC identity token itself, and
expose the same federation inputs as the outer action. Switch the
base-action test workflows from the anthropic_api_key secret to the
federation repo variables and grant them id-token: write.

* Verify MCP test tool invocation instead of init connection status

MCP servers can connect asynchronously, so the init event may report a
server as pending. Check that the server is registered at init, then
assert the test tool was actually called and returned its response.
Also pass the MCP config through claude_args --mcp-config, replacing the
removed mcp_config input.

)

* chore: bump actions/setup-node from v4.4.0 to v6.4.0 (Node.js 24)

setup-node v4 runs on the deprecated Node.js 20 action runtime, producing
a deprecation warning on every workflow run that uses base-action. v6 runs
on Node 24. This only changes the action's own runtime — the node-version
it installs for user code is unaffected.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* Disable setup-node v5+ automatic package-manager caching

Preserves v4 behavior: caching only when use_node_cache=true.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: ant-kurt <209710463+ant-kurt@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

…#1379)

actions/checkout v4 and oven-sh/setup-bun v2.0.2 run on the deprecated
Node 20 action runtime and emit a deprecation warning on every run.
Bump to checkout v6.0.2 and setup-bun v2.2.0 (both Node 24).

Co-authored-by: ant-kurt <209710463+ant-kurt@users.noreply.github.com>