[T-Crypt]

Title: docs: the router editor, the subagents chip, and the two new checks

The README predates the router editor (#7-#10): routers were still described as a drop-in
~/.pi-pocket/extensions/ setup, and there was no router bullet in the Features list at all. It
also predates the subagents chip (#5). And its Development block lists the npm scripts, so it needs
the two scripts this flight adds.

What changed, in README.md only:

• A new Routers bullet in the Features list, after Artifacts and subagents: the fit check and
  the stages, the rail's Routers button (Menu → Routers, the Routers place on a phone), a stage card
  (its template, its words, the skills it reads first, its model, its effort), the built-in
  Standard (Plan, Implement, Review, Fix, Ship), saved routers in
  ~/.pi-pocket/routers/<id>.json, the read-only From this machine routers, Use in this
  session, the model picker's Routers group, and the session running on the router's model
  until a plain model is picked.
• Artifacts and subagents gains the Subagents chip and /subagents: which models they may run
  on besides the session's own.
• Building a router on it now leads with the editor and its prompt written from its stages; the
  drop-ins read as what they add beside it. The four bullets and the docs/extensions.md link are
  unchanged.
• The Development block adds npm run check:web (02: type-check web/ and hold the clean files clean #12) and npm run coverage (03: coverage floor and direct tests for the fence #13) after
  npm test, and its comments are re-padded. Both scripts are in this flight and merge before this
  PR, so the lines are true when it lands; they were read on their own branches before being named.

Every claim in the new text traces to the code: web/routers.js (the editor's own labels),
src/server/routers.ts (Standard, the saved-router path, detected routers),
web/sheets/model.js and web/sheets/menu.js (the picker's Routers group, Menu → Routers),
web/sheets/subagents.js and web/composer.js (the chip and its sheet), and docs/features.md:57.

Proof:

• npm run lint → exit 0.
• npx --no-install prettier --check README.md → "All matched files use Prettier code style!".
• node --test test/docs-examples.test.ts → 4 pass, 0 fail.
• npm run check → exit 0.
• git diff --stat → README.md | 16 ++++++++++------, one file, 10 insertions, 6 deletions.
• Every relative link the README uses still resolves.
• npm test → 630 tests, 627 pass, 3 fail, none of them this change's: one is the
  visible-models-ui router-row race 01: CI runs the repo's checks on push and PR #11 fixes, two are 10 s timeouts in
  test/subagent-policy.test.ts that pass on their own (load on the dev machine).

Open items:

• npm run format:check fails on the base branch (4433a47) over .ome/project.json,
  test/browser.test.ts and test/session-row-ui.test.ts. This PR does not touch them; 01: CI runs the repo's checks on push and PR #11's
  chore(01): format the three files CI's format:check caught fixes them, and 01: CI runs the repo's checks on push and PR #11 merges first.
  If that commit is dropped from 01: CI runs the repo's checks on push and PR #11, this failure comes back on every branch of the flight.
• The README says nothing about the router editor's Advanced section (an own role file per stage, a
  dispatcher-only router, extra words for the router). The Features bullet keeps to the parts a
  reader needs; docs/features.md:57 is the full tour.
• Line 11's Release badge still points at TannerMidd/pi-pocket, the upstream, on the fork's
  README. Left alone: it is a separate change and not part of this review.