fix(kyberforge): resolve agent-author audit findings

Corrects three FAIL findings from the skill-audit run:
- Scope detection table in SKILL.md and references/scripts.md now lists all
  four plugin-marker variants the script actually checks (plugin.json,
  .claude-plugin/plugin.json, .plugin/plugin.json, .github/plugin/plugin.json)
- assets/README.md copilot.agent.md description was wrong about field set;
  replaced with accurate CLI-format description noting excluded cloud/IDE fields
  and the Copilot tool aliases actually used.

Also applies the SUGGESTION: moves the conditional reference
(`If the destination is a plugin directory, read references/deployment-modes.md`)
out of the ## Gotchas section body and into ## Route as a standalone line,
immediately after ## Gotchas closes.

INFO findings (source_keys frontmatter) were already present in both
references/README.md and references/scripts.md — no change needed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0147vXtL5sP6vorDdqXGJJU9

plugins/kyberforge/skills/agent-author/assets/README.md

@@ -5,4 +5,4 @@
 Annotated agent definition templates copied by `scripts/new-agent.sh` when scaffolding a new agent.
 
 - **`claude-code.md`** — Claude Code agent definition template. Includes all supported frontmatter fields (required and optional) with inline guidance comments and `FILL IN:` placeholders. Notes which fields are silently ignored for plugin agents.
-- **`copilot.agent.md`** — Copilot CLI agent definition template. Uses Copilot-specific fields (`target`, `user-invocable`, `disable-model-invocation`, Copilot tool aliases). Explicitly excludes Claude Code-only fields.
+- **`copilot.agent.md`** — Copilot CLI agent definition template (CLI format). Excludes cloud/IDE-only fields (`target`, `user-invocable`, `disable-model-invocation`, `mcp-servers`) and Claude Code-only fields. Uses Copilot tool aliases (`execute`, `read`, `edit`, `search`, `agent`, `web`).