Stop publishing the repo as a plugin marketplace, and refresh the run skill

Three small things.

Removed `.claude-plugin/marketplace.json`. It is the file `/plugin
marketplace add` reads, so without it this repo no longer offers itself as a
marketplace — which is the odd part of an Angular app carrying one. The
caveman plugin's own files stay, so it can be listed from a marketplace of its
own later; only the listing is gone.

That left four documents asserting an install path that no longer exists,
including a README section handing out `/plugin marketplace add` and
`/plugin install` commands that would now fail. All four now say what is
actually true. `.junie/plans/nasa-star-map.md` still describes the repo as
containing only a marketplace, and is left alone: it records what was here
before the app was written, and is not a claim about the present.

The run skill's numbers had drifted a release behind — 496 tests in 28 files
against a real 527 in 31, and a build timed at 9s that now takes 12. Measured
rather than guessed. The pinned Playwright version it names was correct.

It also gains the Pages build, which is not a plain `npm run build`: the base
href and the 404.html copy are both required for a project site, and the
artifact root is `dist/star-map/browser` rather than its parent. Plus the
matching gotcha, since a Pages build served at `/` looks broken in a way that
tells you nothing about whether it would work.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WaySiNst4HhDXBHnMy8p5G

.claude-plugin/marketplace.json

@@ -1,28 +0,0 @@
-{
-  "name": "star-map",
-  "owner": {
-    "name": "avalon-vanguard",
-    "url": "https://github.com/avalon-vanguard"
-  },
-  "description": "Personal marketplace of cs:* Claude Code commands, agents, and skills.",
-  "plugins": [
-    {
-      "name": "caveman",
-      "source": "./",
-      "description": "Ultra-compressed communication mode. Cuts token usage ~75% by dropping filler, articles, and pleasantries while keeping full technical accuracy. Adds a cs-caveman-mode persona agent, /cs:caveman slash command, and stdlib Python tooling (compressor, token-savings estimator, lint) on top of Matt Pocock's MIT-licensed caveman skill.",
-      "version": "1.0.0",
-      "author": {
-        "name": "avalon-vanguard",
-        "url": "https://github.com/avalon-vanguard"
-      },
-      "license": "MIT",
-      "keywords": [
-        "caveman",
-        "communication",
-        "tokens",
-        "productivity"
-      ],
-      "category": "productivity"
-    }
-  ]
-}