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

.gitignore

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+# ── Release workflow helpers ──────────────────────────────────────────────────
+COMMIT.md
+PR.md
+RELEASE.md
+
+# ── Go build artifacts ────────────────────────────────────────────────────────
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+*.test
+*.out
+/dist/
+/bin/
+
+# ── Go workspace (local development only) ────────────────────────────────────
+go.work
+go.work.sum
+
+# ── Dependency vendor directory ───────────────────────────────────────────────
+vendor/
+
+# ── Coverage output ───────────────────────────────────────────────────────────
+coverage.out
+coverage.html
+*.coverprofile
+
+# ── OS artifacts ─────────────────────────────────────────────────────────────
+.DS_Store
+Thumbs.db
+
+# ── Editor artifacts ──────────────────────────────────────────────────────────
+.idea/
+.vscode/
+*.swp
+*.swo
+*~