Merge step (c): converge to ce-* convention for agents and skills

Aligns local custom agents, skills, and modified shared agents with upstream's
flat ce-<name>.agent.md + ce-<skill>/ convention introduced in upstream v3.x.

Changes:
- Delete 9 upstream-renamed agents for locally-dropped agents (design/*, rails
  reviewers, ankane-readme-writer, data-migration-expert, performance-oracle,
  security-sentinel)
- Delete ce-dhh-rails-style skill (local dropped dhh-rails-style entirely)
- Move 5 custom agents to flat ce-<name>.agent.md paths:
  * python-package-readme-writer, design-conformance-reviewer,
    tiangolo-fastapi-reviewer, zip-agent-validator, lint
- Rename 12 custom skill directories with ce- prefix:
  * john-voice, jira-ticket-writer, hugo-blog-publisher, weekly-shipped,
    proof-push, ship-it, story-lens, sync-confluence, excalidraw-png-export,
    python-package-writer, fastapi-style, upstream-merge
- Port local Python/FastAPI edits into upstream's flat ce-best-practices-
  researcher.agent.md and ce-kieran-python-reviewer.agent.md
- Update frontmatter name: fields in all 17 renamed files to match new paths

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

plugins/compound-engineering/agents/ce-lint.agent.md

@@ -0,0 +1,19 @@
+---
+name: ce-lint
+description: "Use this agent when you need to run linting and code quality checks on Python files. Run before pushing to origin."
+model: haiku
+color: yellow
+---
+
+Your workflow process:
+
+1. **Initial Assessment**: Determine which checks are needed based on the files changed or the specific request
+2. **Always check the repo's config first**: Check if the repo has its own linters configured by looking for a pre-commit config file
+3. **Execute Appropriate Tools**:
+   - For Python linting: `ruff check .` for checking, `ruff check --fix .` for auto-fixing
+   - For Python formatting: `ruff format --check .` for checking, `ruff format .` for auto-fixing
+   - For type checking: `mypy .` for static type analysis
+   - For Jinja2 templates: `djlint --lint .` for checking, `djlint --reformat .` for auto-fixing
+   - For security: `bandit -r .` for vulnerability scanning
+4. **Analyze Results**: Parse tool outputs to identify patterns and prioritize issues
+5. **Take Action**: Commit fixes with `style: linting`