docs: address Copilot review round 4 on #2203

Corrects the rationale for the five-positive floor, which was wrong. The
claim was that five prompts make a skill's rate flake-tolerant. The
evaluator scores each prompt on its own `passes / RUNS`, so the number of
prompts never enters any rate and cannot affect a threshold crossing —
`RUNS` is the only knob that does. The floor is worth keeping for
breadth: one prompt measures one phrasing, and a description that fires
on a single narrow shape would pass on its one lucky case.

The bad reasoning had reached five places — AGENTS.md, the authoring
checklist, the JSDoc, the check-site comment and the regression test —
plus the emitted message, which asserted it too. All corrected.

Moves `MIN_POSITIVE_CASES` above `validateEvalCases`'s JSDoc. It had been
inserted between the two, so the `@param`/`@returns` block documented the
constant and the function had none.

Replaces the two remaining cases answerable from `AGENTS.md`: `local-dev`'s
web-client-startup case (the rules file gives the exact command) and
`project-structure`'s clients/web-versus-core case (its tree answers it).
Both replacements probed 3/3 and measure 100%.

RUNS=5 skills:eval: 63/63, every local-dev and project-structure case at
100%. local:gate passes, 34/34.

Signed-off-by: cliffhall <cliff@futurescale.com>

.claude/skills/local-dev/evals/evals.json

@@ -1,6 +1,6 @@
 [
   {
-    "prompt": "How do I get the web client running locally?",
+    "prompt": "What is the difference between the launcher-driven run scripts and starting a client directly, and when should I use each?",
     "expect": "local-dev"
   },
   {

.claude/skills/project-structure/evals/evals.json

@@ -1,6 +1,6 @@
 [
   {
-    "prompt": "What lives in clients/web versus @inspector/core?",
+    "prompt": "This repo has three clients over a shared core. How should I orient myself in it before changing anything?",
     "expect": "project-structure"
   },
   {