docs: drop the tier label from docs that outlived it

[akf66]

There is no add- or remove-label step anywhere in action.yml. Three files still described one — and the one that mattered most is the copy written into every user's repo.

What happened

#28 retired the review cascade and updated workflows/orca-code-review.yml. But the skill keeps its own copy of that workflow in assets/, because that's the file it writes into a user's repo. The example got fixed; the template users actually receive did not.

  workflows/orca-code-review.yml              (fixed by #28)
- issues: write # tier state label + clean/fallback PR comments
+ issues: write # clean/fallback PR comments

  skills/.../assets/workflow.yml              (missed — this is the one users get)
- issues: write # tier state label + clean/fallback PR comments

Fixed

File	Was	Now
skills/.../assets/workflow.yml	# tier state label + clean/fallback PR comments	matches the example
references/inputs.md — github-token	"manages the tier label"	"posts review comments, and reacts to a /orcacode-review command"
references/inputs.md — models	Models | per tier	Model | one
action.yml	"manage the tier label"	the source those two were copied from

issues: write stays

It is still required — just not for the reason the comment gave. It covers PR comments and the emoji reaction on a /orcacode-review command:

repos/$REPO/issues/comments/$COMMENT_ID/reactions

Only the justification was wrong, so only the justification changed.

Left alone, because still true

• x-cr-prev-tier is still injected by the fact proxy. action.yml's own header says the facts and rule shape are kept deliberately, so a future size-based routing policy needs no Action change.
• tier in the run report is still sent — but it is hardcoded standard. inputs.md now says so, otherwise a reader assumes it varies.

Five tests close the gap

The root cause is two copies of one file. So the tests compare them: comment-stripped, the example and the skill template must agree on permissions:, on: and concurrency:, and neither may mention a tier label.

Verified by reverting the fix — neither workflow copy mentions a tier label goes red.

398 passing. 1.3.1: docs-only, but skills/ ships in the npm package, so users keep receiving the wrong comment until it is published.