feat(changelog): configurable sections, scope grouping, commit + compare links

[BryanFRD]

Closes #497

Summary

Adds an opt-in [workspace.changelog] config that enriches changelog/release rendering. Default behaviour is byte-identical to today — with no config, output is the classic three sections (Breaking Changes / Features / Bug Fixes) with flat bullets of full commit subjects, no links, no scope grouping. Everything new is gated behind config.

Config shape

[workspace.changelog]
sections = { feat = "Features", fix = "Bug Fixes", perf = "Performance", security = "Security", docs = false }
group_by_scope = true
include_commit_links = true
include_compare_link = true

• sections: BTreeMap<String, SectionSetting> where a value is a label string OR false (hidden), via an untagged serde enum. Keys are commit-type prefixes (feat/fix/perf/docs/refactor/security). Omitted -> defaults to feat -> Features, fix -> Bug Fixes (Breaking Changes always shown).
• group_by_scope (alias groupByScope), include_commit_links (includeCommitLinks), include_compare_link (includeCompareLink) — all bool, default false. ChangelogConfig derives Default.

Conventions followed (differ from the issue intentionally)

• Section mapping is render-time by commit-type prefix; the bump engine (classify_commit/determine_bump) is untouched. Order: Breaking, Features, Bug Fixes, Performance, Security, then other configured. security takes precedence over fix for fix(security):.
• Scope grouping is inline bold (- **api:** add events endpoint), sorted by scope with scopeless entries first — NOT ### api subheadings.
• No Deprecated/Removed sections — no conventional-commits signal to derive them.
• Commit links ([<hash>](<forge>/commit/<hash>)) and compare footer [<ver>]: <forge>/compare/<last>...<new> only when the forge is resolvable; forge-unknown silently omits them (no error).
• Breaking entries render the BREAKING CHANGE: footer body when richer mode is active (subject-only under default).

Tests

default_render_is_byte_identical_to_classic proves the no-config path equals the classic renderer. Added coverage for perf/security/docs/feat! sections, security precedence, inline scope grouping, commit links (present + forge-unknown omitted), compare link (present + no-last-tag omitted), custom labels, breaking-footer body, plus config parsing (TOML + camelCase, untagged false). All pre-existing src/changelog.rs tests pass unchanged.

Schema

Updated schema/ferrflow.json with workspace.changelog. The FerrFlow-Cloud mirror (public/schema/ferrflow.json) is not touched here — handled separately.

[github-actions]

Benchmark

Details

Benchmark suite	Current: be4ef01	Previous: 0b5fe57	Ratio
commit_parsing/100	16895 ns/iter (± 1132)	17091 ns/iter (± 38)	0.99
commit_parsing/1000	171630 ns/iter (± 792)	174058 ns/iter (± 2250)	0.99
commit_parsing/10000	1718674 ns/iter (± 6380)	1809492 ns/iter (± 18830)	0.95

This comment was automatically generated by workflow using github-action-benchmark.