docs: add ROADMAP.md with two forward-looking feature candidates

feat: Kustomize + Helm manifest bundles as release artifacts (spec-015) (#20)

docs: complete tasks phase — Kustomize + Helm manifest bundles (spec-015)

docs: complete plan phase — Kustomize + Helm manifest bundles (spec-015)

docs: complete specify phase — Kustomize + Helm manifest bundles (spec-015)

docs: README documentation hub split (spec-014) (#19)

chore: remove vestigial IDEA.md, update AGENTS.md project description

docs: complete tasks phase — README documentation hub split (spec-014)

docs: complete plan phase — README documentation hub split (spec-014)

docs: complete specify phase — README documentation hub split (spec-014)

docs(constitution): amend Principle X — README as Documentation Hub with docs/ Articles (v2.8.0 → v2.9.0)

fix: artifact inventory governance + equalizer publish workflow

ci: 4-cluster equalizer E2E — cross-cluster scenarios from the spec (#18)

docs(spec-013): documentation fixes — source tree, erw-verify scenarios, cross-cluster guide (#17)

feat: multi-cluster capacity equalizer — fleet-level budget optimization (spec-013) (#16)

docs(spec-013): complete tasks phase — implementation handoff (48 tasks)

docs(spec-013): agent-context hook — point AGENTS.md/CLAUDE.md at spec-013 plan

docs(spec-013): complete plan phase — multi-cluster equalizer design artifacts

docs(spec-013): multi-cluster capacity equalizer — spec + quality checklist

feat: per-resource budget tracking — independent CPU/RAM budgets (spec-012) (#15)