chore(cli): bump to v0.2.6 + revert unrelated __init__.py docstring

Addresses review feedback on #5152:

  - Revert the mem0/__init__.py module docstring (was a misguided
    workaround to fire ci.yml; reviewer correctly flagged as unrelated)
  - Bump cli-python and cli-node to 0.2.6 so the claim-flow tip wording
    fix ships to users in the next release
  - Add CLI v0.2.6 changelog entry under docs/changelog/sdk.mdx

The build_mem0/build_embedchain required-check stalemate on docs-only
PRs needs a proper ci.yml fix in a separate PR (passthrough job for
the path-filter-skipped case). Admin override needed for this PR.

cli/python/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "mem0-cli"
-version = "0.2.5"
+version = "0.2.6"
 description = "The official CLI for mem0 — the memory layer for AI agents"
 readme = "README.md"
 license = "Apache-2.0"