feat(workflow): add late join test workflow with 5000 inserts and verification

[rtb-12]

[Core] Add late-join test workflow for KV store

Description

Adds a workflow that tests late-join sync: Node 1 performs 5000 inserts, then Node 2 joins and verifies all entries are synced and accessible.

The workflow (apps/kv-store/workflows/late-join-test.yml) covers:

• 5000 inserts on Node 1 before Node 2 joins
• Late join of Node 2 after all inserts complete
• Verification that all 5000 entries sync to Node 2
• Assertions that specific keys (first, middle, near-end, last) are accessible on Node 2
• Cross-verification that Node 1 still has all entries after sync

This tests the sync protocol's ability to catch up a late-joining node with a large state history.

Test plan

Documentation update

No documentation changes required .

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Note

Introduces an end-to-end late-join sync test for the KV store.

• New workflow apps/kv-store/workflows/late-join-test.yml spins up 2 nodes and installs res/kv_store.wasm
• Performs 5000 set operations on Node 1, verifies len == 5000
• Creates identity for Node 2, invites and joins the context, then wait_for_sync across nodes
• Verifies Node 2 len == 5000, checks entries contains sample keys, and validates specific get results (key_1, key_2499, key_4999, key_5000)
• Cross-check ensures Node 1 still reports len == 5000 post-sync

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