feat!: modernize for Go 1.26 and prepare v1.0.0

[christiangda]

Summary

Reworks RamStorage (r9e) for Go 1.26, fixes correctness bugs, adds new capabilities, and brings the repository in line with the slashdevops open-source layout (e5t / comparator). This is intended as the v1.0.0 release.

The library stays dependency-free (standard library only).

🐞 Correctness fixes

• Deadlocks removed in MapKeyValue: Clone, Map, Filter, Partition, DeepEqual, and sorting previously held RLock() and then re-acquired it (recursive read lock, which Go warns can deadlock when a writer is waiting). They now build results under a single lock or via a snapshot.
• SMapKeyValue.Size() over-count fixed: the counter no longer increments when overwriting an existing key.
• Counter race fixed: decrements now use an atomic Add(-1) (atomic.Int64) instead of a non-atomic load-then-swap.
• Clear() uses sync.Map.Clear / the clear builtin instead of reallocating.

🆕 New features

• All() range-over-func iterators (iter.Seq2[K, T]) on both containers.
• GetOrSet (atomic get-or-insert), Merge, and JSON support (MarshalJSON / UnmarshalJSON).
• Modern stdlib internals: maps, slices, clear, atomic.Int64.

💥 Breaking changes (pre-1.0 → 1.0.0)

Before	After
go 1.19	go 1.26
GetAnDelete	GetAndDelete
IsFull()	removed — use !IsEmpty()
Key()	removed — use ContainsKey()
SortKeys() []*K	SortKeys() []K
SortValues() []*T	SortValues() []T

Full before/after guide: docs/migration.md.

📚 Docs & tooling

• New doc.go (replaces godoc.go); every method documented.
• Extensive docs/ guides with mermaid diagrams (getting-started, containers, concurrency, operations, iteration, json, performance, migration, faq).
• Richer README.md: full badge row, install/update via go get, API tables, mermaid, What's New / Breaking Changes.
• Modernized Makefile (pretty output, grouped help, lint/vulncheck/betteralign/tool-install targets).
• AGENTS.md (symlink → .github/copilot-instructions.md) with the post-change checklist.
• GitHub Actions: main / pr / release / codeql (actions v7 / codeql v4), dependabot, .golangci.yaml; removed gosec and legacy codeql-analysis.

✅ Verification

go vet ./...      # clean
go test -race ...  # PASS — coverage 97.8%
go build ./...    # OK

🤖 Generated with Claude Code

[github-advanced-security]

You are seeing this message because GitHub Code Scanning has recently been set up for this repository, or this pull request contains the workflow file for the Code Scanning tool.

What Enabling Code Scanning Means:

• The 'Security' tab will display more code scanning analysis results (e.g., for the default branch).
• Depending on your configuration and choice of analysis tool, future pull requests will be annotated with code scanning analysis results.
• You will be able to see the analysis results for the pull request's branch on this overview once the scans have completed and the checks have passed.

For more information about GitHub Code Scanning, check out the documentation.