docs: replace legacy perf table in en index

docs: soften aggressive zero-allocation wording

docs: remove exaggerated vocabulary

docs: clarify message vs record header architecture and blueprint

docs: Modernize legacy syntax safely

docs: Update terminology and architectural parity

docs: fix markdown bold parsing, update protobuf status and add security section

docs: add elixir 1.7.1 benchmark measurements

docs: update feature matrix and milestone for v1.7.0 (Elixir/Security)

docs: add Elixir tutorial guide

docs: add episode 3 on protocol security and large payload strategy

docs: Comprehensive update for Elixir and Java reference spec and security bounds

docs: use joygram@gmail.com and professional b2b cta in license

docs(site): adjust cover images to be moderately sized and center-aligned

docs(site): add balanced semantic cover images to all strategic guides and articles