docs: sync support policy with v0.2 state

[CoderDeltaLAN]

Summary

• Sync SUPPORT.md with the published v0.2.0 GitHub Release line.
• Remove stale pre-release/no-stable-public-release wording.
• Preserve conservative support boundaries: no stable support/API guarantee, no SLA, no production readiness claim, no security guarantees, no PyPI publication claim, and private vulnerability reporting remains documented as disabled.

Verification

• ./scripts/check.sh
• workflow_dispatch CI on branch for SHA 9