Ship native subagent definitions for GitHub Copilot and Cursor

The github and cursor providers previously received only the generated
degraded/ inline fallbacks. Both harnesses support real custom subagents,
so the build now emits them from the same skill/agents/ source:

- GitHub Copilot: .github/agents/impeccable-<role>.agent.md with portable
  frontmatter only (name + description; omitting tools grants all tools,
  and Copilot has no documented model/effort/max-turns equivalents).
- Cursor: .cursor/agents/impeccable-<role>.md with name, description,
  model: inherit, is_background: false, and readonly derived from the
  agent's tool list (true only for the finish reviewer, which declares
  neither Write nor Edit). effort/max-turns are skipped because Cursor's
  effort option requires an explicit model id.

Agent bodies now also resolve {{scripts_path}} and strip rule markers in
the shared agentFormat pipeline, which fixes the previously unresolved
placeholder in the emitted Claude asset-producer agent.

The CLI installer places agents per scope: project installs write
<repo>/.github/agents/ and <repo>/.cursor/agents/; user-level installs
write ~/.copilot/agents/ (Copilot's user dir, not ~/.github/) and
~/.cursor/agents/, overwriting stale impeccable-* copies. Because
Copilot lets user-level agents shadow same-named project ones, a project
install warns when shadowing copies exist; Cursor gives project agents
precedence, so no warning there.

new-work.md and visualize.md extend their harness-naming clauses with
the Cursor and Copilot invocations. The degraded/ fallbacks keep
shipping for surfaces where the model still fails to delegate.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/lib/transformers/providers.js

@@ -16,6 +16,10 @@ export const PROVIDERS = {
     configDir: '.cursor',
     displayName: 'Cursor',
     frontmatterFields: ['license', 'compatibility', 'metadata'],
+    // Cursor subagents: `.cursor/agents/<name>.md` at repo level,
+    // `~/.cursor/agents/` at user level. Project agents take precedence over
+    // user ones, so installs simply overwrite on update.
+    agentFormat: 'cursor-md',
     emitHooks: 'cursor',
     // Cursor reads `.cursor/hooks.json`, not `.cursor/hooks/hooks.json`.
     hooksManifestRel: 'hooks.json',
@@ -68,6 +72,11 @@ export const PROVIDERS = {
     displayName: 'GitHub Copilot',
     placeholderProvider: 'agents',
     frontmatterFields: ['user-invocable', 'argument-hint', 'license', 'compatibility', 'metadata'],
+    // Copilot custom agents: `.github/agents/<name>.agent.md` at repo level,
+    // `~/.copilot/agents/` at user level (the CLI installer handles placement).
+    // The degraded/ fallbacks still ship for Copilot surfaces where the model
+    // fails to delegate; the .agent.md files are the real subagent path.
+    agentFormat: 'copilot-agent-md',
     emitHooks: 'github',
     // GitHub Copilot discovers repo-level hooks under `.github/hooks/*.json`.
     hooksManifestRel: 'hooks/impeccable.json',