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

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.

internal/tools/tools.go

@@ -19,6 +19,7 @@ func Register(s *mcp.Server, idx *index.Index) {
 	registerListADRs(s, idx)
 	registerGetADR(s, idx)
 	registerGetExample(s, idx)
+	registerGetScaffold(s, idx)
 	registerValidateSnippet(s, idx)
 	registerGetCompliance(s, idx)
 	registerGetChangelog(s, idx)