fix: align Small-tier plan-review rule and changelog wording

Resolve two consistency nits from review: shape-spec said plan-review was
'optional' for Small while the README canonical table says skip it (align
to skip); and the changelog now describes both misuse directions the new
rationalizations guard against, not just gate-skipping.

CHANGELOG.md

@@ -15,8 +15,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   the non-negotiable rule (`verification-gate` and `code-review-loop` always run,
   any tier); `shape-spec` gains a `Step 0: Size the change` routing gate;
   `write-plan` and `plan-review` declare which tier they belong to; each of the
-  three carries a new rationalization against skipping the gate under the "it's
-  trivial" excuse
+  three carries a new rationalization against misusing the tier model — skipping
+  the evidence gate under an "it's trivial" excuse, or over-applying full ceremony
+  to a one-liner
 
 ### Added
 

skills/shape-spec/SKILL.md

@@ -55,9 +55,8 @@ change is how the missing constraint ships.
    - **Trivial** — one-line / single-file / describable in one sentence. **Stop
      here — no spec.** Make the change, then go straight to `verification-gate`
      and `code-review-loop`.
-   - **Small** — one focused change, ≤ ~3 files, design obvious. **Skip the spec**
-     and hand off to `write-plan` for a lightweight inline plan; `plan-review` is
-     optional at this tier.
+   - **Small** — one focused change, ≤ ~3 files, design obvious. **Skip the spec
+     and plan-review**; hand off to `write-plan` for a lightweight inline plan.
    - **Standard** — multi-file, multi-session, or real design decisions. Continue
      to Step 1 and write the full spec.
 2. Whatever the tier, the evidence never scales to zero: `verification-gate` runs