docs: cut the Workflow section to what nothing else supplies

[lesnik512]

Why

The Workflow section states three things this repo already states elsewhere, and
AGENTS.md is loaded on every turn.

The ADR and issue routes are written twice. docs/agents/domain.md
already says "a rejected alternative → an ADR; real work you are not doing now → a
GitHub issue. Nothing else gets written", and then points back here for the admission
check. docs/agents/issue-tracker.md owns the gh
usage. The circularity is the tell.

NNNN-slug.md, sequential is supplied by the domain-modeling skill's ADR format,
which is what docs/agents/domain.md configures. Restating it here means it rots in
two places at once, which is what the same file warns about four sections down.

"There is no change file, no lane to choose, and no planning/ tree" describes
three directories that do not exist. Derivable from the source, therefore not written.
The same goes for "no truth-home directory".

Design

Cut to what nothing else supplies:

• The body shape (why, design, non-goals, verification) stays. No skill defines it;
  it is this org's own convention and the one line with measured effect. PRs ci: run pytest on pull requests, with rsvg-convert available #62, ci: check external links weekly, opening an issue when one dies #63
  and ci: gate PRs on local links, and stop publishing the ADRs #65 came out in that shape while this repo's PR template said
  Summary/Changes/Checklist, because AGENTS.md is read every turn and the
  template never is.
• The two routes stay as one sentence, because the exactly-two-homes framing is the
  constraint; the numbering and gh mechanics become a pointer to docs/agents/.
• "with a revisit trigger" stays. The skill's ADR format does not include it, so
  it is genuinely this repo's own rule and has no other home.
• The negative clauses go.

Nine lines become seven, and the two duplications become one pointer.

Non-goals

• Not removing the revisit-trigger rule. Delete the local PR templates; keep the generic org default #53 decided not to
  propagate it to the other repos. Removing it here is a change to this repo's own ADR
  practice and is a separate call.
• Not touching docs/agents/. The pointer direction is AGENTS.md → docs/agents/;
  the reverse pointer in domain.md (back here for the admission check) is correct,
  since the admission check has no other home.
• Not touching the Where a fact goes table. Its docs/adr/ row overlaps the
  Workflow paragraph, but the table is the admission check itself and is load-bearing.

Verification

uv run pytest: 123 passed, 26 skipped, 5 failed. The five are PNG rendering and
reproduce unchanged on main — rsvg-convert and pngquant are not installed
locally; CI installs them. This change touches no Python.

The one new link, docs/agents/, is a directory that exists and is already linked
the same way from this file's Agent skills section. The links job (offline lychee
over **/*.md) is the gate.