feat(middleware,ci): add OTEL middleware, CI/pre-commit; bump Go 1.25.5

[hyp3rd]

• Introduce pkg/middleware with OTEL tracing and stats scaffolding
• Set up GitHub Actions (lint, test, security) and Dependabot
• Add .golangci.yaml, cspell config, and pre-commit hooks (gci, gofumpt,
  govulncheck, go mod tidy/verify)
• Add .project-settings.env and wire into Makefile to pin toolchain
  (GO_VERSION=1.25.5, GOLANGCI_LINT_VERSION=v2.7.2)
• Update go.mod to Go 1.25.5; upgrade deps: fiber v3.0.0-rc.3,
  go-redis v9.17.2, msgpack v2.4.0, x/crypto v0.46.0, ewrap v1.3.2
• Refactor internals: normalize transport.Client parameter order,
  adjust cluster.NewNode signature, and simplify slice bounds in
  distributed memory with min(...)
• Reorder imports and apply formatting; minor docs/cleanup

[Copilot]

Pull request overview

This PR introduces significant infrastructure and distributed backend improvements to HyperCache:

Purpose: Add OpenTelemetry middleware, comprehensive CI/CD pipeline, pre-commit tooling, upgrade to Go 1.25.5 (problematic version), and refactor the distributed memory backend with rebalancing capabilities.

Key Changes:

• Introduce pkg/middleware with OTEL tracing scaffolding
• Set up GitHub Actions workflows for linting, testing, and security scanning
• Add pre-commit hooks and development tooling configuration
• Upgrade dependencies (fiber v3 RC, redis, msgpack, crypto libs)
• Implement distributed memory rebalancing with replica diff logic
• Refactor transport interfaces and cluster node creation

Reviewed changes

Copilot reviewed 78 out of 79 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
go.mod/go.sum	Bump to Go 1.25.5 (invalid version) and upgrade dependencies
.github/workflows/*	Add comprehensive CI pipelines (lint, test, security, pre-commit)
.pre-commit/*	Add pre-commit hooks for gci, golangci-lint, go mod verification
.project-settings.env	Pin toolchain versions for consistency
pkg/backend/dist_memory.go	Major rebalancing implementation with replica diff and shedding logic
pkg/cache/v2/*	Rename package from cachev2 to v2 (breaking change)
tests/benchmark/*	Update benchmark loops to use b.Loop() (invalid API)
pkg/middleware/*	Consolidate package documentation into middleware.go
Makefile	Enhance with security scanning, proto support, toolchain management
docs/distributed.md	Add comprehensive distributed backend documentation

Comments suppressed due to low confidence (1)

pkg/backend/dist_memory.go:1743

• The function signature has an incorrect duplicate closing brace at line 1728 followed by an opening brace and wg.Add(1) at line 1730. This creates a syntax error - the goroutine function body starts at line 1719 with wg.Go() but there's also a conflicting go func() at line 1730. These two concurrent execution patterns are duplicated and will not compile.

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[Copilot]

The package declaration changed from "cachev2" to "v2", but this breaks the expected import path. Go modules should use a versioned directory path (e.g., "v2" in the directory name) with a package name that matches or is reasonable. Changing the package name from "cachev2" to "v2" is unconventional and may cause import confusion. The package should typically remain "cachev2" or match the directory name convention.

[Copilot]

The benchmark loop pattern changed from "for range b.N" to "for b.Loop()" but b.Loop() is not a standard method in Go's testing.B type. The standard benchmark loop pattern is "for range b.N" (Go 1.22+) or "for i := 0; i < b.N; i++" (older). This will cause compilation errors.

[Copilot]

The spelling error "callbacalled" should be corrected to "called back" or "callback called". The comment currently reads "IterCb is the iterator callbacalled for every key,value found in" which is not a valid word.