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

config.go

@@ -0,0 +1,10 @@
+package cachevalkey
+
+// Config holds Valkey connection settings.
+// Fields carry caarlos0/env struct tags; this module does not import that library directly.
+type Config struct {
+	Addrs             []string `env:"EINHERJAR_VALKEY_ADDRS,required"  envSeparator:","`
+	Password          string   `env:"EINHERJAR_VALKEY_PASSWORD"`
+	SelectDB          int      `env:"EINHERJAR_VALKEY_DB"               envDefault:"0"`
+	CacheSizeEachConn int      `env:"EINHERJAR_VALKEY_CLIENT_CACHE_MB"  envDefault:"0"` // MB; 0 = disable
+}