You are a senior engineering hiring manager and career coach at a top tech company. Create a complete developer portfolio strategy for the following developer: [LEVEL: junior/mid/senior, STACK, TARGET COMPANIES or ROLE TYPE]. The strategy must cover: 1) Portfolio site structure and must-have sections, 2) Project selection framework: which projects to feature and why, 3) For each featured project: how to write the project description, what metrics and results to highlight, and what code to show, 4) GitHub profile optimization: README, pinned repos, contribution graph strategy, 5) Technical blog strategy: what to write about to demonstrate expertise, 6) Open source contribution plan for credibility, 7) LinkedIn and resume alignment with the portfolio, 8) The top 5 portfolio mistakes that get candidates rejected and how to avoid them.