Add acreadiness-cockpit plugin (AgentRC measure -> generate -> maintain) 🤖🤖🤖 (#1593)

* Add acreadiness-cockpit plugin

Adds a new plugin that drives Microsoft AgentRC from Copilot chat,
framing every interaction inside AgentRC's Measure -> Generate ->
Maintain loop.

Custom agent (agents/ai-readiness-reporter.agent.md):
  Runs `agentrc readiness --json`, interprets every result against
  the 9-pillar / 5-level maturity model, then renders a self-contained
  reports/index.html from a fixed HTML/CSS template (bundled with the
  acreadiness-assess skill) so every user gets an identically styled
  dashboard. Honours policies (disabled criteria, overrides, pass-rate
  thresholds) and surfaces extras separately.

Skills:
  - acreadiness-assess: Measure step. Wraps `agentrc readiness --json`
    and hands off to the @ai-readiness-reporter agent. Bundles the
    canonical report-template.html.
  - acreadiness-generate-instructions: Generate step. Wraps
    `agentrc instructions`. Defaults to .github/copilot-instructions.md
    (Copilot-native). Asks flat vs nested. For monorepos, emits per-area
    .github/instructions/<area>.instructions.md files with applyTo
    globs taken from agentrc.config.json.
  - acreadiness-policy: Maintain step. Helps pick, scaffold, or apply an
    AgentRC policy (criteria.disable, criteria.override, extras,
    thresholds) and wire it into CI via --fail-level.

Plugin (plugins/acreadiness-cockpit/):
  Declarative plugin.json referencing the agent and three skills.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Address PR review feedback

- Align documented slash-command names with plugin manifest:
  /acreadiness-assess, /acreadiness-generate-instructions,
  /acreadiness-policy (was /assess, /generate-instructions, /policy
  inside SKILL bodies and argument-hints).
- Move the literal % from the report template into the substituted
  values for {{passRate}} and {{threshold}} so an N/A value of '—'
  no longer renders as '—%'. Updated the agent placeholder contract
  accordingly.
- Point the report footer at the canonical plugin folder under
  github/awesome-copilot instead of the personal source fork.
- Add explicit HTML-escaping rules to the agent: HTML-escape every
  {{placeholder}} substitution, and replace </script with <\/script
  inside the embedded JSON block so untrusted repo content cannot
  break the markup or inject scripts.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/plugin/marketplace.json

@@ -10,6 +10,12 @@
     "email": "copilot@github.com"
   },
   "plugins": [
+    {
+      "name": "acreadiness-cockpit",
+      "source": "acreadiness-cockpit",
+      "description": "Drive Microsoft AgentRC from Copilot chat: assess AI readiness, generate Copilot instructions (flat or nested with applyTo globs for monorepos), and manage policies. Produces a self-contained static HTML dashboard at reports/index.html.",
+      "version": "1.0.0"
+    },
     {
       "name": "ai-team-orchestration",
       "source": "ai-team-orchestration",