feat(mcp): derive env vars from the framework's real struct tags

Minor to v1.1.0. Make the whole environment-variable surface derive from the
indexed component-config tags instead of a hand-maintained list that drifts.
Also folds in the scaffold-symbol fixes staged as v1.0.1 (never tagged); the
generated scaffold compiles clean against einherjar v1.0.0.

internal/envspec (new):
- Parse index struct tags into env vars {name, module, struct, field, required,
  default}. One source of truth: ParseTag, ForModule, FindStruct, All, KnownNames.

internal/tools:
- get_config_env: list the real env vars a component config reads (or all).
- check_env: flag unknown EINHERJAR_* names, required vars missing for the
  composed modules, and dead vars (set for an uncomposed module).
- get_scaffold: .env.example is now DERIVED from the index — required vars
  uncommented with a dev value, defaulted vars commented with their default.
  The scaffold now composes logz.Config (Log logz.Config) so EINHERJAR_LOG_*
  are live and documented, not hardcoded/ignored (log format is env-driven).
- validate_snippet: inject the real env-var name set into the rules package.

internal/index/builtins (wire conventions):
- Route the incremental "compose a component later" flow to get_config_env /
  check_env; distinguish framework EINHERJAR_* from app-owned APP_* (JWT).
- Compose logz.Config in the config + Run() examples, to match the scaffold.

internal/rules:
- config.unknown-env-var (twelfth rule): reject an env:"EINHERJAR_*" struct tag
  the framework doesn't declare. No-op until the server injects the name set, so
  it never fires on incomplete knowledge.

Fixed (was v1.0.1): scaffold health hook + wire builtin used logz.Logger (real:
contracts/logging.Logger) and postgres.Component (hooks take Provider); env tags
were EINHERJAR_SERVER_ADDR / EINHERJAR_PG_DATABASE (real: _HOST/_PORT / _PG_NAME).

Tests: envspec unit tests; env tools against the real data/index.json; the rule.
Verified by generating the scaffold, building it against local einherjar v1.0.0
(exit 0), and runtime-loading the composed logz.Config (EINHERJAR_LOG_LEVEL=DEBUG
-> slog.LevelDebug, EINHERJAR_LOG_JSON=true). Version bumped to v1.1.0 (badge +
serverVersion). No dependency changes.

README.md

@@ -1,6 +1,6 @@
 # einherjar/mcp
 
-[![version](https://img.shields.io/badge/version-v1.0.0-5C4EE5?style=flat-square)](https://code.nochebuena.dev/einherjar/mcp)
+[![version](https://img.shields.io/badge/version-v1.1.0-5C4EE5?style=flat-square)](https://code.nochebuena.dev/einherjar/mcp)
 [![license](https://img.shields.io/badge/license-AGPL--3.0-22863A?style=flat-square)](LICENSE)
 [![go](https://img.shields.io/badge/Go-1.26+-00ADD8?style=flat-square&logo=go&logoColor=white)](https://go.dev)
 
@@ -38,7 +38,7 @@ under pressure.
 
 ## Tools
 
-The server exposes **eleven** tools to MCP-aware clients (Claude desktop, Claude Code,
+The server exposes **thirteen** tools to MCP-aware clients (Claude desktop, Claude Code,
 Cursor, Zed, and anything else that speaks MCP):
 
 | Tool | Purpose |
@@ -50,16 +50,19 @@ Cursor, Zed, and anything else that speaks MCP):
 | `list_adrs` | List architectural decision records, optionally restricted to one module |
 | `get_adr` | Fetch a single ADR's markdown body |
 | `get_example` | Canonical usage snippet — pulled from module READMEs and from the synthetic `wire` conventions |
-| `get_scaffold` | The canonical **minimum application scaffold** as ready-to-write files — a clean `main.go`, `internal/wire/wire.go`, a composed `internal/config`, a health hook, and `.env.example`. Use it when starting a new Einherjar service |
+| `get_scaffold` | The canonical **minimum application scaffold** as ready-to-write files — a clean `main.go`, `internal/wire/wire.go`, a composed `internal/config`, a health hook, and a **`.env.example` derived from the real component-config tags**. Use it when starting a new Einherjar service |
+| `get_config_env` | The **real** env vars a component config reads — name, declaring module/struct/field, required, and default — derived from the framework's struct tags. The source of truth for building a global config or a `.env` |
+| `check_env` | Check a `.env` / `.env.example` against the framework: flags EINHERJAR_* names that don't exist (e.g. `EINHERJAR_PG_DATABASE`), missing required vars for the modules you compose, and vars set for a module you don't compose |
 | `get_compliance` | Interface assertions and structural test names from a module's `compliance_test.go` |
 | `get_changelog` | Full `CHANGELOG.md` markdown for one module |
 | `validate_snippet` | Pattern-match a Go snippet against framework conventions; returns findings with severity, hint, and line |
 
-`validate_snippet` ships **eleven** wiring-convention rules at v1.0.0:
+`validate_snippet` ships **twelve** wiring-convention rules:
 `launcher.missing-run`, `launcher.no-components`, `launcher.run-error-discarded`,
 `logz.direct-env-read`, `web.server-not-appended`, `wire.hook-bad-signature`,
 `wire.hook-outside-beforestart`, `wire.route-specific-after-param`,
-`main.dirty`, `main.no-godotenv-autoload`, and `config.raw-getenv`.
+`main.dirty`, `main.no-godotenv-autoload`, `config.raw-getenv`, and
+`config.unknown-env-var` (rejects an `env:"EINHERJAR_*"` tag the framework doesn't declare).
 
 ---