restructure docs: split triggers into usage pages, add model resolution docs

- split triggers.mdx into direct-prompting, pr-reviews, issue-enrichment, coding-tasks
- rename manual-setup.mdx to headless-action.mdx (CI integration)
- reorganize sidebar into Getting started / Usage / Reference groups
- add redirects for /triggers and /manual-setup
- add PULLFROG_MODEL env var support across action, workflows, and docs
- rewrite models.mdx with aliases, free models, resolution chain, routers
- update all cross-references in app, components, and docs

Made-with: Cursor

agents/opentoad.ts

@@ -75,7 +75,7 @@ function buildSecurityConfig(ctx: AgentRunContext, model: string | undefined): s
 // ── model resolution (see wiki/model-resolution.md) ─────────────────────────────
 //
 // priority:
-//   1. OPENCODE_MODEL env var (explicit override)
+//   1. PULLFROG_MODEL or OPENCODE_MODEL env var (explicit override)
 //   2. explicit slug from repo config / payload
 //   3. auto-select: `opencode models` → recommended aliases first, then secondary
 //   4. undefined → let OpenCode decide
@@ -106,10 +106,11 @@ function resolveOpenCodeModel(ctx: {
   cliPath: string;
   modelSlug?: string | undefined;
 }): string | undefined {
-  // 1. explicit env var override
-  const envModel = process.env.OPENCODE_MODEL?.trim();
+  // 1. explicit env var override (PULLFROG_MODEL takes precedence over OPENCODE_MODEL)
+  const envModel = process.env.PULLFROG_MODEL?.trim() || process.env.OPENCODE_MODEL?.trim();
   if (envModel) {
-    log.info(`» model: ${envModel} (override via OPENCODE_MODEL)`);
+    const source = process.env.PULLFROG_MODEL?.trim() ? "PULLFROG_MODEL" : "OPENCODE_MODEL";
+    log.info(`» model: ${envModel} (override via ${source})`);
     return envModel;
   }