fix(bin): put five skills' boundaries where the router can read them

grill-me, grill-with-docs, improve-codebase-architecture, tdd and triage each had
their routing boundary written into README.md, which nothing loads at runtime,
while the gate still reported all five descriptions as boundary-less. The
boundaries move into the descriptions; write-docs' clause, which said 'those have
dedicated skills' without naming one, now names them.

research had moved its body out and then read both references unconditionally --
the anti-goal ADR-0020 names, where the word count moves and the per-run context
does not. Both loads are genuinely conditional now, with the topic list and the
four literal sources.md field names inlined, since the provenance validator
matches those literally.

Also restores the promote-the-prototype anti-pattern to prototype's ui.md, which
the gate does not measure, so deleting it bought nothing.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EJJrm5YmacbwMdzZpXcoti

plugins/bin/skills/grill-with-docs/SKILL.md

@@ -1,6 +1,9 @@
 ---
 name: grill-with-docs
-description: Grilling session that challenges your plan against the existing domain model, sharpens terminology, and updates documentation (CONTEXT.md, ADRs) inline as decisions crystallise. Use when user wants to stress-test a plan against their project's language and documented decisions.
+description: >
+  Use when a plan should be stress-tested against the project's domain model —
+  the interview challenges terms against `CONTEXT.md` and writes decisions into
+  it and into ADRs as they land. Not a plain interview -> `grill-me`.
 ---
 
 <what-to-do>