fix: context-size /compact trigger, Codex marketplace plugin path, live README badges (#2237)

- suggest-compact hook now reads the latest usage record from the session
  transcript and suggests /compact at a window-scaled token threshold
  (160k/200k window, 250k/1M window; COMPACT_CONTEXT_THRESHOLD and
  COMPACT_CONTEXT_INTERVAL overridable), re-firing per 60k-token growth
  bucket; tool-call count stays as the secondary signal (#2155)
- Codex repo marketplace now points at ./plugins/ecc instead of ./ — Codex
  never discovers plugins whose local marketplace source.path is the
  marketplace root (verified on Codex CLI 0.137.0); plugins/ecc is a thin
  folder referencing root skills/.mcp.json per maintainer direction on
  #2097; docs flag plugin mode as experimental with the upstream blocker
  openai/codex#26037 linked (#2128)
- README badges for installs/stars/forks now use shields endpoint badges
  backed by api.ecc.tools (live install count 3,712 vs the stale static
  150), which also eliminates shields' 'Unable to select next GitHub token
  from pool' render in the stars badge

Closes #2155
Closes #2128

plugins/ecc/README.md

@@ -0,0 +1,41 @@
+# plugins/ecc — Codex Repo-Marketplace Plugin Target
+
+This directory is the plugin folder that `.agents/plugins/marketplace.json`
+points at. Codex does not discover plugins whose local marketplace
+`source.path` is the marketplace root itself (`./`), so the marketplace entry
+must target a concrete plugin subdirectory — verified against Codex CLI
+0.137.0 and the official plugin docs (`$REPO_ROOT/plugins/<name>`).
+
+## Single source of truth
+
+Per the repo's no-duplication policy, no skill or MCP content is vendored
+here. `.codex-plugin/plugin.json` references the canonical root content with
+parent-relative paths:
+
+| Manifest field | Resolves to |
+|---|---|
+| `skills` | `skills/` at the repo root |
+| `mcpServers` | `.mcp.json` at the repo root |
+| `interface.composerIcon` / `interface.logo` | `assets/` at the repo root |
+
+The canonical Codex plugin manifest for the repo-root bundle (used by the
+official `openai/plugins` directory shape and other harness tooling) remains
+at `.codex-plugin/plugin.json`. Keep `name` and `version` in both manifests in
+sync — `tests/plugin-manifest.test.js` enforces this and `scripts/release.sh`
+bumps both.
+
+## Current Codex plugin-mode status
+
+With this layout, `codex plugin marketplace add affaan-m/ECC` discovers and
+installs `ecc@ecc`. Runtime skill loading from repo marketplaces is still
+unreliable upstream — Codex copies only the plugin folder into its install
+cache, and local/personal marketplace plugins are not always exposed at
+runtime (see [openai/codex#26037](https://github.com/openai/codex/issues/26037)
+and [affaan-m/ECC#2128](https://github.com/affaan-m/ECC/issues/2128)).
+
+Until the upstream discovery issues settle, the supported Codex path is the
+manual sync flow documented in the README:
+
+```bash
+npm install && bash scripts/sync-ecc-to-codex.sh
+```