content(blog): publish agentic identity part 2 and rewrite its intro

[axsaucedo]

Part 2 of the Agentic Security & Identity series has sat on master dated 2026-12-31, so the live page was a noindex preview. This sets the date to today so it publishes in time to be the hook for newsletter 407.

It also reworks the intro and the series refresher, which read too much like default LLM prose. The opening now starts from Part 1 and says in first person what this part checks, the aphorism pull quote and the 'honest caveat up front' line are gone, and the rule-of-three lists are replaced with plain statements of what goes wrong with a shared bot token. Everything from the decisions table onwards is untouched.

npm run check:voice passes locally. I haven't rendered the page; the change is prose and one frontmatter date.

[github-actions]

Visual parity — light theme ☀️

Every captured route is pixel-identical to the merge base across 1440x1000 (40 routes) and 420x900 (40 routes).

Informational: label the PR visual-change to state that pixels are meant to move, or dependencies to require zero.

[github-actions]

Visual parity — dark theme 🌙

1440x1000 — 1 of 40 routes moved.

Route	Differing pixels	Peak channel delta
talks-and-events.png	49,400	236/255

420x900 — 0 of 40 routes moved.

Differing pixels locate a change; the peak channel delta sizes it. A large count with a
delta of 1–2/255 is a sub-perceptual shift, a small count at 200/255 is something a reader
would see.

Informational: label the PR visual-change to state that pixels are meant to move, or dependencies to require zero.