Add focused EdgeFlow portfolio and reviewer guidance

[hanklin9188]

Summary

EdgeFlow's existing README and validation stack are already comprehensive. This PR adds bounded entry points for interviewers and technical reviewers, then closes the package-manifest gap exposed by the new files.

What changed

• add PORTFOLIO.md with the problem, engineering contribution, key design decisions, evidence status, code-review path, and five-minute demo
• add REVIEWER_GUIDE.md with 5-, 15-, and 30-minute review paths plus research-method questions
• add LIMITATIONS.md covering hardware, workload, quality, timing, thermal, causal, kernel, policy, learned-component, control-plane, and external-validation scope
• add a push-only manifest synchronization workflow using the repository's existing generator and validator
• update the main CI matrix to regenerate the manifest before package validation
• refresh PACKAGE_MANIFEST.json so all 190 public files, including the new review material and workflow, are hash-tracked

Claim discipline

• retained RTX 4080 SUPER runs remain capability/integration evidence where marked CONDITIONAL_PASS
• no cross-runtime winner or universal deployment recommendation is added
• profiler output remains a hypothesis until matched intervention evidence exists
• custom-kernel correctness remains distinct from end-to-end model speedup
• the recommended next 3×3 evidence package is labelled as a future promotion target, not a completed result

Verified on this PR

• Actions run #131: PASS
• Python 3.11, 3.12, and 3.13: PASS for uv sync, Ruff, pytest, regenerated manifest, package validation, and result verification
• security job: PASS for secret, model-weight, and profiler-binary rejection
• manifest bot successfully produced the current head and increased tracked files from 186 to 190
• branch is 7 commits ahead of main, 0 behind, and GitHub reports it mergeable
• Markdown-link validation is covered by the existing package validator