chore: modernize workflows, security scanning, and linting configuration (#50)

* build: update Go 1.25, CI workflows, and build tooling

- Upgrade to Go 1.25
- Add benchmark targets to Makefile
- Implement parallel gosec execution
- Lock tool versions for reproducibility
- Add shellcheck directives to scripts
- Update CI workflows with improved caching

* refactor: migrate from golangci-lint to revive

- Replace golangci-lint with revive for linting
- Configure comprehensive revive rules
- Fix all EditorConfig violations
- Add yamllint and yamlfmt support
- Remove deprecated .golangci.yml

* refactor: rename utils to shared and deduplicate code

- Rename utils package to shared
- Add shared constants package
- Deduplicate constants across packages
- Address CodeRabbit review feedback

* fix: resolve SonarQube issues and add safety guards

- Fix all 73 SonarQube OPEN issues
- Add nil guards for resourceMonitor, backpressure, metricsCollector
- Implement io.Closer for headerFileReader
- Propagate errors from processing helpers
- Add metrics and templates packages
- Improve error handling across codebase

* test: improve test infrastructure and coverage

- Add benchmarks for cli, fileproc, metrics
- Improve test coverage for cli, fileproc, config
- Refactor tests with helper functions
- Add shared test constants
- Fix test function naming conventions
- Reduce cognitive complexity in benchmark tests

* docs: update documentation and configuration examples

- Update CLAUDE.md with current project state
- Refresh README with new features
- Add usage and configuration examples
- Add SonarQube project configuration
- Consolidate config.example.yaml

* fix: resolve shellcheck warnings in scripts

- Use ./*.go instead of *.go to prevent dash-prefixed filenames
  from being interpreted as options (SC2035)
- Remove unreachable return statement after exit (SC2317)
- Remove obsolete gibidiutils/ directory reference

* chore(deps): upgrade go dependencies

* chore(lint): megalinter fixes

* fix: improve test coverage and fix file descriptor leaks

- Add defer r.Close() to fix pipe file descriptor leaks in benchmark tests
- Refactor TestProcessorConfigureFileTypes with helper functions and assertions
- Refactor TestProcessorLogFinalStats with output capture and keyword verification
- Use shared constants instead of literal strings (TestFilePNG, FormatMarkdown, etc.)
- Reduce cognitive complexity by extracting helper functions

* fix: align test comments with function names

Remove underscores from test comments to match actual function names:
- benchmark/benchmark_test.go (2 fixes)
- fileproc/filetypes_config_test.go (4 fixes)
- fileproc/filetypes_registry_test.go (6 fixes)
- fileproc/processor_test.go (6 fixes)
- fileproc/resource_monitor_types_test.go (4 fixes)
- fileproc/writer_test.go (3 fixes)

* fix: various test improvements and bug fixes

- Remove duplicate maxCacheSize check in filetypes_registry_test.go
- Shorten long comment in processor_test.go to stay under 120 chars
- Remove flaky time.Sleep in collector_test.go, use >= 0 assertion
- Close pipe reader in benchmark_test.go to fix file descriptor leak
- Use ContinueOnError in flags_test.go to match ResetFlags behavior
- Add nil check for p.ui in processor_workers.go before UpdateProgress
- Fix resource_monitor_validation_test.go by setting hardMemoryLimitBytes directly

* chore(yaml): add missing document start markers

Add --- document start to YAML files to satisfy yamllint:
- .github/workflows/codeql.yml
- .github/workflows/build-test-publish.yml
- .github/workflows/security.yml
- .github/actions/setup/action.yml

* fix: guard nil resourceMonitor and fix test deadlock

- Guard resourceMonitor before CreateFileProcessingContext call
- Add ui.UpdateProgress on emergency stop and path error returns
- Fix potential deadlock in TestProcessFile using wg.Go with defer close

scripts/security.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+
+# Shared security scanning functions
+
+# Run gosec in parallel on all Go directories
+run_gosec_parallel() {
+  local exit_code=0
+  local pids=()
+  local go_dirs=("./benchmark" "./cli" "./cmd" "./config" "./fileproc" "./metrics" "./shared" "./templates" "./testutil" ".")
+
+  # Start gosec for each directory in background
+  for dir in "${go_dirs[@]}"; do
+    # Skip non-existent directories
+    if [[ ! -d "$dir" ]]; then
+      continue
+    fi
+
+    if [[ "$dir" == "." ]]; then
+      # For root directory, scan only .go files directly (not subdirectories)
+      gosec -fmt=text -quiet -exclude-dir=vendor -exclude-dir=.git -exclude-dir=benchmark -exclude-dir=cli -exclude-dir=cmd -exclude-dir=config -exclude-dir=fileproc -exclude-dir=metrics -exclude-dir=shared -exclude-dir=templates -exclude-dir=testutil . >"gosec_${dir//\//_}.log" 2>&1 &
+    else
+      # For subdirectories, exclude vendor and .git
+      gosec -fmt=text -quiet -exclude-dir=vendor -exclude-dir=.git "$dir" >"gosec_${dir//\//_}.log" 2>&1 &
+    fi
+    pids+=($!)
+  done
+
+  # Wait for all gosec processes to complete and check their exit codes
+  for i in "${!pids[@]}"; do
+    local pid="${pids[$i]}"
+    local dir="${go_dirs[$i]}"
+    if ! wait "$pid"; then
+      echo "gosec failed for directory: $dir"
+      cat "gosec_${dir//\//_}.log"
+      # Keep log for inspection/artifacts on failure
+      exit_code=1
+    else
+      # Clean up log file if successful
+      rm -f "gosec_${dir//\//_}.log"
+    fi
+  done
+
+  return $exit_code
+}
+
+# If this file is sourced, export the functions
+if [[ "${BASH_SOURCE[0]}" != "${0}" ]]; then
+  export -f run_gosec_parallel
+fi