docs: prioritize npm-based Quick Start for published package

chore: rebrand CLI/package from mcp-firewall to mcpsieve with alias

docs: update branding links for MCPSieve

docs: add contributor guide and issue/pr templates

docs: add canonical release-check CLI snippets

docs: add clone step to Quick Start

docs: standardize README Quick Start heading

docs: rewrite README for public launch clarity

docs: improve README first-run UX

feat(policy): add actor/context constraints and transport context propagation

fix(policy): normalize encoded HTTP path separators (#3)

fix: canonicalize forwarded http json bodies (#2)

fix(cli): align mode-effective exits and enforce audit fixture projection

feat: add mode-aware audit snapshots and audit fixture generation

feat(cli): add compare delta-handoff-portal token