chore(release): prepare 0.9.0

[Lythaeon]

Description

This PR prepares the 0.9.0 release surface.

It bumps the published SOF crate versions, aligns the internal dependency pins, refreshes the vendored gossip fork version used by sof-observer, and updates the README install snippets to match the release.

Changes

• crates/sof-gossip-tuning/Cargo.toml

  • bumped sof-gossip-tuning from 0.8.1 to 0.9.0

• crates/sof-observer/Cargo.toml

  • bumped sof from 0.8.1 to 0.9.0
  • bumped internal sof-gossip-tuning dependency to 0.9.0
  • bumped vendored gossip dependency from sof-solana-gossip 3.1.8-sof.2 to 3.1.8-sof.3

• crates/sof-tx/Cargo.toml

  • bumped sof-tx from 0.8.1 to 0.9.0
  • bumped internal sof dependency to 0.9.0

• crates/sof-solana-gossip/Cargo.toml

  • bumped vendored gossip crate version from 3.1.8-sof.2 to 3.1.8-sof.3

• crates/sof-solana-gossip/Cargo.toml.orig

  • kept the original vendored manifest in sync with the published version bump

• Cargo.lock

  • refreshed the workspace lockfile to the 0.9.0 / 3.1.8-sof.3 release surface

• Docs

  • README.md
  • crates/sof-observer/README.md
  • crates/sof-tx/README.md
  • updated dependency snippets from 0.8.1 to 0.9.0

For slice-related changes, include:

• Affected slices
  • release/versioning surface only
• Cross-slice communication changes (if any) and why
  • none; this PR aligns versions and release docs without changing runtime behavior
• Migration requirements (if any)
  • downstream users updating to 0.9.0 should use the new crate versions in dependency declarations

Motivation

Business motivation:

• Prepare a clean 0.9.0 release branch with consistent published versions and documentation.

Technical motivation:

• Keep workspace crate versions aligned.
• Ensure internal dependency pins match the next release.
• Publish the current vendored gossip fork under a new patch version reflecting the shipped code.

Alternative approaches considered:

• Partial version bump. Rejected because it leaves the release surface inconsistent.
• Reuse the prior vendored gossip version. Rejected because the current release surface carries additional vendored-gossip changes and should publish under a new patch suffix.

Scope and impact

• Affected slices:
  • release manifests
  • lockfile
  • README install/version snippets
• Data/API changes:
  • crate version numbers only
• Backward compatibility:
  • no runtime/API change in this PR itself
  • consumers must update dependency versions to 0.9.0
• Performance impact:
  • none
• Security impact:
  • none

Testing

• Unit tests
• Integration tests
• Manual verification
• Performance checks (if applicable)
• Security checks (if applicable)

Commands/results:

cargo make ci
cargo check --workspace --locked

Both passed locally.

Related issues and documentation

• Fixes:
• Related:
• Architecture docs: docs/architecture/README.md
• Relevant ARD/ADR:
• Operations/runbook updates: README.md, crates/sof-observer/README.md, crates/sof-tx/README.md

Reviewer checklist

• Code follows project standards and architecture constraints
• Slice boundaries are respected (docs/architecture/ard/0003-slice-dependency-contracts.md)
• Tests added/updated and passing
• Documentation updated (README/docs/operations as needed)
• No undocumented breaking change
• Performance trade-offs documented where relevant
• Security considerations addressed where relevant

Additional notes

Trade-offs, follow-up work, or deviations from standards.

• This branch is intentionally narrow: release/version alignment only.
• Runtime and feature changes for 0.9.0 are already in main; this PR just prepares the publishable version surface.