chore: close out v0.6 adoption

[ehsanestaji]

Scoped change description

Close out the FastaGuard v0.6 adoption cycle and establish a clean baseline for the next development round.

• synchronize release, packaging, workflow, and adoption documentation with the published v0.6.0 state
• preserve the reviewer-approved nf-core and Snakemake four-report contract and downstream JSON or TSV gating
• add a portable five-case public evidence summary with explicit source and observed-binary provenance boundaries
• prepare and validate the local MultiQC plugin distribution without publishing it
• add community health files and remove internal planning or tool-memory artifacts from the tracked tree
• strengthen CI coverage for release metadata, evidence, workflow integrations, packaging, and repository hygiene

Tests

• cargo fmt --check
• cargo test --locked: 160 passed
• cargo clippy --locked --all-targets --all-features -- -D warnings
• isolated Python suite: 91 tests and 102 subtests passed
• focused post-history audit: 83 tests and 100 subtests passed
• Snakemake 9.25.2 starter execution: exactly four nonempty reports, WARN report exit 0, no legacy exit artifact
• Python 3.10.20 and 3.14.5 with MultiQC 1.28 and 1.35: passed
• local Bioconda recipe and core nf-core or Snakemake assets match current upstream

Nextflow and nf-test were unavailable locally. Their accepted upstream module files match byte-for-byte, and the static and executable contract suites pass.

Contract impact

• No public FastaGuard report or CLI contract change.
• Public contract changed; JSON, TSV, HTML, schema, and finding catalog impacts are described above.

Documentation impact

• No documentation change is needed.
• Documentation, examples, and release metadata were updated.

Review checklist

• Tests cover changed behavior or explain why tests are not applicable.
• DCO: every commit includes a Signed-off-by line.
• Attribution-trace review: the change has no unwanted authorship or tool-provenance traces.
• The contribution stays within FastaGuard FASTA-level preflight scope.