feat: add plugin marketplace and screenshot redesign workflow

[cat0825]

Summary

• Add Claude Code plugin marketplace manifests for installing the repo through /plugin marketplace add Leonxlnx/taste-skill and /plugin install taste-skill@taste-skill.
• Add redesign-imagegen-codex, a screenshot-first Codex redesign workflow using Chrome DevTools MCP or browser screenshots before generating references and implementing changes.
• Update brandkit so it asks whether brand assets already exist and supports create-from-scratch, build-on-existing-brand, and partial-input extension modes.

Issues covered

• Addresses [FR] Add redesign-imagegen-codex #14
• Addresses Proposal: make the repo a Claude Code plugin marketplace (2 small files) #18
• Addresses brandkit skill should ask whether a brand already exists before generating a full kit #19

Notes

• I skipped issues already covered by open PRs: v1: LAYOUT_VARIANCE should be DESIGN_VARIANCE in anti-center bias rule #36 has fix: LAYOUT_VARIANCE -> DESIGN_VARIANCE in v1 anti-center bias rule #37/fix(v1): rename LAYOUT_VARIANCE to DESIGN_VARIANCE in anti-center rule (#36) #40, refactor: extract appendices to reference/ files #38 has refactor: extract appendices to reference/ files #39, and Add examples of each skill? #15 has Add skill showcase — visual examples of all web design skills #21.
• I did not change Please create a template skill #23 because the owner asked for clarification, and the scope is not yet concrete.
• I did not duplicate (feature request) - Add an accessibility skill in some way #32 because open PR Add accessibility, performance, SEO, dark mode & code examples #3 already covers accessibility-related skill changes, though it is currently conflicted.

Validation

• git diff --check
• python3 -m json.tool .claude-plugin/plugin.json
• python3 -m json.tool .claude-plugin/marketplace.json
• claude plugin validate .
• zsh skill.sh redesign-imagegen-codex
• zsh skill.sh brandkit

Generated by Codex.

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