Graduate wayfinder to engineering; unify changesets for v1.1

Graduate `wayfinder` out of in-progress into the engineering bucket
(plugin.json, top-level + Engineering READMEs under User-invoked, docs
page, ask-matt on-ramp, disable-model-invocation).

Consolidate the 22 pending changesets into 10 coherent v1.1 entries:
one `wayfinder` (rename from decision-mapping + full reframe +
graduation), one `grilling`, one `code-review`, one `tdd`; fold the
superseded to-issues changeset into unify-to-tickets and drop its stray
`</content>` tag. Highest bump is minor → 1.0.1 becomes 1.1.0.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.claude-plugin/plugin.json

@@ -10,6 +10,7 @@
     "./skills/engineering/tdd",
     "./skills/engineering/to-spec",
     "./skills/engineering/to-tickets",
+    "./skills/engineering/wayfinder",
     "./skills/engineering/implement",
     "./skills/engineering/prototype",
     "./skills/engineering/research",