feat(cache-valkey): initial implementation — Provider, adapters (v1.0.0)

Introduces code.nochebuena.dev/einherjar/cache-valkey — the Valkey cache starter
for the Einherjar framework. Absorbs the valkey package from micro-lib and adds
three duck-typed adapters that wire directly into auth, web, and auth-jwt.

Core:
- Provider interface — Get, Set, Del, Exists, Expire, IncrWithTTL, Native()
- Component interface — lifecycle.Component + observability.Checkable + Provider
- Config struct (EINHERJAR_VALKEY_* env vars)
- New(logger, cfg) Component — creates valkey-go client in OnInit;
  PING in OnStart; logs "valkey: connected"
- IncrWithTTL implemented with Lua script (atomic INCR + conditional EXPIRE);
  race-free fixed-window semantics with no MULTI/EXEC overhead
- Priority: LevelDegraded — Valkey outage degrades, does not halt the service

Adapters (duck-typed — no import of auth, web, or auth-jwt):
- PermissionCache — Get/Set int64 bitmasks as string; satisfies auth/rbac.Cache
- RateLimiterStore — fixed-window via IncrWithTTL; satisfies web/mw.RateLimiterStore
- Blacklist — Exists/Set "1" with TTL; satisfies auth-jwt.Blacklist

Compliance test verifies CT-6, duck-type shape assignments, and full adapter
behavioural coverage with a mockProvider (no live server required).

- Component interface embeds observability.Identifiable; identifiable.go implements
  ModulePath and ModuleVersion via runtime/debug.ReadBuildInfo() — prints in launcher banner

doc.go

@@ -0,0 +1,27 @@
+// Package cachevalkey provides a lifecycle-aware Valkey client with health checks
+// and three adapters that integrate with other Einherjar starters via duck typing.
+//
+// # Quick start
+//
+//	vk := cachevalkey.New(logger, cfg)
+//	launcher.Register(vk) // lifecycle: OnInit → OnStart → OnStop
+//	health.Register(vk)   // health: PING-based, LevelDegraded
+//
+// # Adapters
+//
+// Each adapter wraps the Provider and satisfies one interface in another module.
+// Go's structural typing handles the assignment — no cast required:
+//
+//	permCache   := cachevalkey.NewPermissionCache(vk)             // → auth/rbac.Cache
+//	rateLimiter := cachevalkey.NewRateLimiterStore(vk, time.Second, 100) // → web/mw.RateLimiterStore
+//	blacklist   := cachevalkey.NewBlacklist(vk)                   // → auth-jwt.Blacklist
+//
+// # Configuration
+//
+// Config fields carry caarlos0/env struct tags. Populate via environment variables
+// or construct directly:
+//
+//	cfg := cachevalkey.Config{
+//	    Addrs: []string{"localhost:6379"},
+//	}
+package cachevalkey