feat(skills): add academic-paper-review, code-documentation, and newsletter-generation skills

[ademakdogan]

Summary

Add three new public skills to enhance DeerFlow's content creation and analysis capabilities. These skills are purely additive — no existing code or configuration is modified.

New Skills

Skill	Description	Lines
academic-paper-review	Structured peer-review-quality analysis of research papers following top-venue review standards (NeurIPS, ICML, ACL). 3-phase workflow: Comprehension → Critical Analysis → Synthesis.	289
code-documentation	Professional documentation generation for software projects (README, API reference, architecture docs, inline docs). Supports Python, TypeScript, Go, Rust, Java, and C++ conventions.	415
newsletter-generation	Curated newsletter creation with research workflow. Supports daily digest, weekly roundup, deep-dive, and industry briefing formats with audience-specific tone adaptation.	343

Compliance

• ✅ All three pass _validate_skill_frontmatter() validation
• ✅ Existing 18 skill validation tests remain passing
• ✅ Hyphen-case naming consistent with existing skills
• ✅ Only allowed frontmatter properties used (name, description)
• ✅ YAML frontmatter follows the exact convention of existing public skills
• ✅ No changes to any existing files or backend code
• ✅ Each skill includes comprehensive workflow phases, quality checklists, output templates, and examples

Motivation

These skills align with the Q2 Roadmap goals for expanding DeerFlow's capabilities. The skill system is designed for this type of extensibility — each skill is a self-contained SKILL.md file under skills/public/ with zero coupling to the core harness.

Testing

# Official validation passes for all 3 skills
uv run python3 -c "
from pathlib import Path
from deerflow.skills.validation import _validate_skill_frontmatter
for s in ['academic-paper-review', 'code-documentation', 'newsletter-generation']:
    valid, msg, name = _validate_skill_frontmatter(Path(f'../skills/public/{s}'))
    print(f'{s}: {msg}')
"
# Output:
# academic-paper-review: Skill is valid!
# code-documentation: Skill is valid!
# newsletter-generation: Skill is valid!

# Existing tests pass
uv run pytest tests/test_skills_validation.py -v  # 18 passed

[CLAassistant]

All committers have signed the CLA.

[Copilot]

Pull request overview

Adds three new additive public skills (SKILL.md under skills/public/) to expand DeerFlow’s content creation and analysis capabilities via the skill-loader system.

Changes:

• Add academic-paper-review skill for structured, top-venue-style paper reviews.
• Add code-documentation skill for generating READMEs, API docs, architecture docs, and inline docs.
• Add newsletter-generation skill for curated newsletters across common formats (digest/roundup/briefing/deep-dive).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
skills/public/academic-paper-review/SKILL.md	New skill guide for producing structured academic paper reviews (templates + QA checklist).
skills/public/code-documentation/SKILL.md	New skill guide for codebase-driven documentation generation (README/API/architecture/inline docs).
skills/public/newsletter-generation/SKILL.md	New skill guide for research-backed newsletter planning, curation, writing, and output handling.

[WillemJiang]

@ademakdogan, thanks for your contribution.