docs: examples for every hard requirement + mort migration blueprint

Phase 7: nine runnable examples/ programs (parse, failover chains with
trailing alias, tiers, LLM_* env providers, multimodal, tool loop,
Generate[T], agent, skills); docs/mort-migration.md mapping mort's
go-llm/go-agentkit usage onto majordomo APIs with the planned additive
library extensions and conversion order; README finalized with the
complete matrix.

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

examples/failover/main.go

@@ -0,0 +1,44 @@
+// Command failover demonstrates ordered failover chains with health
+// tracking — including the README's flagship examples: a plain chain and
+// the same chain with a registered alias expanded inline at the tail.
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"log"
+
+	"gitea.stevedudenhoeffer.com/steve/majordomo"
+)
+
+func main() {
+	flag.Parse()
+
+	reg := majordomo.New()
+	reg.RegisterAlias("thinking", "anthropic/opus-4.8,ollama-cloud/minimax-m3:cloud")
+
+	// Plain chain: try head-to-tail. One transient blip on a target is
+	// retried in place; repeated failures bench the target (exponential
+	// cooldown) and the chain advances.
+	plain := "ollama-cloud/minimax-m3:cloud,ollama-cloud/kimi-k2.6:cloud,anthropic/opus-4.8"
+
+	// Same chain with the registered alias appended: "thinking" expands
+	// inline as the tail (duplicates are dropped, first occurrence wins).
+	withAlias := plain + ",thinking"
+
+	for _, spec := range []string{plain, withAlias} {
+		m, err := reg.Parse(spec)
+		if err != nil {
+			log.Fatalf("parse %q: %v", spec, err)
+		}
+		resp, err := m.Generate(context.Background(), majordomo.Request{
+			Messages: []majordomo.Message{majordomo.UserText("In one sentence: why do failover chains beat single targets?")},
+		})
+		if err != nil {
+			// The joined error names every target and why it failed.
+			log.Fatalf("chain exhausted:\n%v", err)
+		}
+		fmt.Printf("spec: %s\n  served by %s: %s\n\n", spec, resp.Model, resp.Text())
+	}
+}