docs: publish detailed public beta validation and README refresh

[adgk2349]

Summary

FlowMap has been prepared for Public Beta with updated docs and validation artifacts.

Changes

• Replaced screenshots across English/Korean/Japanese READMEs (.jpg)
• Refreshed English/Korean/Japanese READMEs for Public Beta positioning and validation links
• Added contributor onboarding documents/templates:
  • CONTRIBUTING.md
  • .github/PULL_REQUEST_TEMPLATE.md
  • .github/ISSUE_TEMPLATE/*
  • docs/good-first-issues.md
• Added detailed validation report generator:
  • scripts/build_validation_detail.mjs
• Added/updated validation result artifacts:
  • reports/replay-validation-bundle.{md,json}
  • reports/sample-scenarios-report.json
  • reports/public-beta-validation-detail.{md,json}

Validation

Executed:

node scripts/build_replay_summary.mjs \
  --report reports/replay-heavy-swift-full-strict.json \
  --report reports/replay-flowmap-75.json \
  --report reports/replay-kdecoder.json \
  --json-out reports/replay-validation-bundle.json \
  --md-out reports/replay-validation-bundle.md

node scripts/run_sample_scenarios.mjs \
  --report reports/sample-scenarios-report.json

node scripts/build_validation_detail.mjs \
  --replay-report reports/replay-heavy-swift-full-strict.json \
  --replay-report reports/replay-flowmap-75.json \
  --replay-report reports/replay-kdecoder.json \
  --scenario-report reports/sample-scenarios-report.json \
  --json-out reports/public-beta-validation-detail.json \
  --md-out reports/public-beta-validation-detail.md

Results:

• Replay total pairs: 209
• TP / TN / FP / FN: 106 / 97 / 0 / 6
• Non-Swift FP Rate: 0%
• Swift Detection Rate: 94.64%
• Overall Match Rate: 97.13%
• Sample scenarios: 60/60 PASS (FP 0, FN 0)
• Public Beta Gate: PASS

Notes

• The 6 replay non-pass entries are warn_swift_no_graph_change in non-strict mode (warnings, not hard failures).