ci: overhaul workflows - lint, security scanning, release hardening

- add golangci-lint job to go.yml (parallel with build+test)
- add Go 1.23/1.24 version matrix, coverage only on 1.24
- upgrade setup-go@v4 to v5, codecov@v4 to v5 across all workflows
- fix check-large-files bug (find|while never exits 1), exclude .git/
- add concurrency groups to push+PR workflows (no duplicate runs)
- lowercase all workflow names to match project voice
- add gosec, errorlint, gocognit, nilnil, wastedassign, usetesting linters
- remove deprecated exportloopref (Go 1.22 fixed loop var capture)
- new: govulncheck.yml - Go vuln scanner with call-graph analysis
- new: scorecard.yml - OpenSSF supply chain scorecard
- new: dependabot.yml - auto-update Go deps + Actions versions
- release: SHA256 checksums + SBOM generation for all artifacts
- add CODEOWNERS

.github/workflows/misspell.yml

@@ -1,10 +1,14 @@
-name: Misspell Check
+name: misspell check
 
 on:
   pull_request:
   push:
     branches: [main]
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   misspell:
     name: runner / misspell