feat(mcp): scaffold tool, config/env conventions, and scaffold-hygiene rules (#2)

Major release to v1.0.0, aligned with the v1.0.0 framework. The MCP documented
the wiring conventions but not the config half of a project, and its example
main.go omitted the godotenv autoload — so an assistant starting a service from
zero still hand-rolled main.go and the launcher, and got config wrong. This adds
a first-class scaffold, completes the config/.env.example conventions, and adds
rules that catch the "mess in main" pattern.

internal/tools:
- New get_scaffold: returns the canonical minimum application scaffold as
  ready-to-write files (main.go with godotenv autoload + wire.Run(), wire.go,
  a composed config.go, a health hook, .env.example), with import paths filled
  from a `module` argument. Registered in tools.go.

internal/rules:
- Three new validate_snippet rules, appended in scaffold_rules.go: main.dirty
  (launcher/components built in main instead of internal/wire),
  main.no-godotenv-autoload (a wire-convention main that never loads .env), and
  config.raw-getenv (an EINHERJAR_* var read via os.Getenv instead of composing
  the component Config; EINHERJAR_LOG_* stays with logz.direct-env-read).
- scaffold_rules_test.go — internal/rules had no tests; asserts each new rule
  fires and that a clean main is not flagged.

internal/index (builtins):
- The synthetic wire module gains a Config section (compose the framework's
  component configs, load with caarlos0/env, APP_* app fields / EINHERJAR_*
  framework fields) and a Config & .env.example discipline (every env var the
  config reads is documented in .env.example, kept in lock-step).
- main.go now shows the `_ "github.com/joho/godotenv/autoload"` blank import,
  previously omitted. The assembly file is renamed launcher.go -> wire.go.
- Migrations and seeding removed from the documented scaffold — developer
  choices, not framework conventions. Re-synced against iron-dough-api / pei-api.

Version:
- Badge and serverVersion const were stale at v0.1.0; both now v1.0.0.

Docs:
- README (eleven tools, eleven validation rules) and CHANGELOG updated.

No new dependencies. The wire conventions are embedded at build time
(//go:embed builtins/README.md) and the new tool and rules are compiled in, so a
deployment must be rebuilt to serve them; a server still running the v0.2.0
binary keeps serving the old conventions until redeployed.

Reviewed-on: #2
Co-authored-by: Rene Nochebuena Guerrero <rene@nochebuena.dev>
Co-committed-by: Rene Nochebuena Guerrero <rene@nochebuena.dev>

internal/rules/scaffold_rules_test.go

@@ -0,0 +1,81 @@
+package rules
+
+import "testing"
+
+func hasRule(fs []Finding, id string) bool {
+	for _, f := range fs {
+		if f.RuleID == id {
+			return true
+		}
+	}
+	return false
+}
+
+func TestMainDirty_flagsLauncherInMain(t *testing.T) {
+	src := `package main
+
+import (
+	"code.nochebuena.dev/einherjar/core/launcher"
+	"code.nochebuena.dev/einherjar/core/logz"
+)
+
+func main() {
+	logger := logz.New(logz.Config{})
+	lc := launcher.New(logger)
+	_ = lc.Run()
+}`
+	if !hasRule(Run(src), "main.dirty") {
+		t.Fatal("expected main.dirty when the launcher is constructed in main")
+	}
+}
+
+func TestCleanMain_isNotFlagged(t *testing.T) {
+	src := `package main
+
+import (
+	"os"
+
+	_ "github.com/joho/godotenv/autoload"
+
+	"myapp/internal/wire"
+)
+
+func main() {
+	if err := wire.Run(); err != nil {
+		os.Exit(1)
+	}
+}`
+	fs := Run(src)
+	if hasRule(fs, "main.dirty") {
+		t.Fatal("clean main must not trip main.dirty")
+	}
+	if hasRule(fs, "main.no-godotenv-autoload") {
+		t.Fatal("clean main has autoload; must not trip main.no-godotenv-autoload")
+	}
+}
+
+func TestMainNoGodotenv_flagsMissingAutoload(t *testing.T) {
+	src := `package main
+
+import "myapp/internal/wire"
+
+func main() {
+	_ = wire.Run()
+}`
+	if !hasRule(Run(src), "main.no-godotenv-autoload") {
+		t.Fatal("expected main.no-godotenv-autoload when .env is never loaded")
+	}
+}
+
+func TestConfigRawGetenv_flagsEinherjarVar(t *testing.T) {
+	src := `package config
+
+import "os"
+
+func Load() string {
+	return os.Getenv("EINHERJAR_PG_HOST")
+}`
+	if !hasRule(Run(src), "config.raw-getenv") {
+		t.Fatal("expected config.raw-getenv when an EINHERJAR_* var is read via os.Getenv")
+	}
+}