[codex] Mark v0.3 packaging live

[ehsanestaji]

Summary

• Update README, packaging, adoption, roadmap, release, and landscape docs now that FastaGuard v0.3.0 is live on Bioconda and BioContainers.
• Promote Bioconda and BioContainers as the primary install paths for v0.3.0.
• Update nf-core/Snakemake starter docs and add the pinned v0.3 BioContainers image to the local nf-core module example.
• Refresh the local Bioconda recipe mirror to the published v0.3.0 recipe and source SHA.
• Update tests so stale pending-v0.3 wording cannot return in current docs.

Verified live package state

• Bioconda latest: 0.3.0
• Bioconda platforms: linux-64, linux-aarch64, osx-64, osx-arm64
• BioContainers tag: quay.io/biocontainers/fastaguard:0.3.0--hfa8f182_0

Test Plan

• python3 -m unittest discover tests/python -v
• cargo fmt --check
• cargo test --locked
• cargo clippy --locked --all-targets --all-features -- -D warnings
• git diff --check
• trailing whitespace scan
• stale pending-v0.3 wording scan across current docs/examples/packaging