add nodejs/node ncrypto sync workflow

[panva]

This:

• updates the GHA dependency pins
• introduces a workflow_dispatch sync job for pulling nodejs/node state in here
• includes its first bootstrapped run (0b0ecca) and resolved merge conflicts (ce5b003)

The sync script maps these Node.js files into this repository:

• deps/ncrypto/ncrypto.h -> include/ncrypto.h
• deps/ncrypto/ncrypto.cc -> src/ncrypto.cpp
• deps/ncrypto/engine.cc -> src/engine.cpp

The script performs a 3-way merge rather than blindly copying files:

• base: the previous nodejs/node commit recorded in .github/sync-node-ncrypto.json
• ours: the current standalone ncrypto file in this repository
• theirs: the requested target nodejs/node ref

This applies the Node-side changes from base to theirs onto the standalone files while preserving standalone-only edits when possible.

On the first bootstrap run (panva#6), .github/sync-node-ncrypto.json had no recorded Node commit, so base_node_ref was supplied manually. After a successful sync, the script records the resolved target Node commit in that state file, allowing future runs to infer the merge base automatically.

The script also checks whether nodejs/node added new deps/ncrypto C/C++ source or header files that are not mapped into this repository. If it finds any, it fails rather than silently omitting files.

If a 3-way merge produces conflicts, the conflicted files are still written with diff3 conflict markers, and the workflow opens the PR as a draft for manual resolution.