feat: rename project from Validatrix to Nimcheck across all files and add CI pipeline

Rename the entire project from "Validatrix" to "Nimcheck" in README.md, Makefile, LESSONS_LEARNED.md, and all source references; add initial Gitea CI workflow with lint, test, and build jobs for Nim 2.0.0; expand .gitignore with comprehensive patterns for Nim, Python, editor, environment, and temporary files; add CONTRIBUTING.md and LICENSE (MIT) files to establish project governance and licensing.

.gitignore

@@ -1,31 +1,83 @@
-# Compiled binaries
-bin/
+# ── Nim ──────────────────────────────────────────────────────────────────
+nimcache/
+nimblecache/
+*.exe
 *.out
-
-# Logs
-*.log
-
-# Python cache
-__pycache__/
-*.pyc
-
-# OS files
-.DS_Store
-Thumbs.db
-
-# Build artifacts
 *.o
 *.obj
 *.a
 *.so
+*.dylib
 
-# Test compiled binaries (source is .nim, binaries have no extension)
+# ── Binaries (compiled output) ───────────────────────────────────────────
+bin/
+
+# ── Test compiled binaries (source is .nim, binaries have no extension) ──
 tests/test_all
 tests/test_bash
 tests/test_nim
 tests/test_php
+tests/test_python
+tests/test_javascript
+tests/test_js
+tests/test_html
+tests/test_jinja
+tests/test_json
+tests/test_yaml
+tests/test_toml
+tests/test_mixed
+tests/test_config
+tests/test_fuzz
 
-# Editor files
+# ── Logs ─────────────────────────────────────────────────────────────────
+*.log
+
+# ── Python cache ─────────────────────────────────────────────────────────
+__pycache__/
+*.pyc
+*.pyo
+*.pyd
+
+# ── OS files ─────────────────────────────────────────────────────────────
+.DS_Store
+.DS_Store?
+._*
+.Spotlight-V100
+.Trashes
+ehthumbs.db
+Thumbs.db
+desktop.ini
+
+# ── Editor files ─────────────────────────────────────────────────────────
 *.swp
 *.swo
 *~
+*.bak
+*.orig
+.vscode/
+.idea/
+*.sublime-project
+*.sublime-workspace
+
+# ── Environment / secrets ────────────────────────────────────────────────
+.env
+.env.local
+.env.*.local
+*.env
+!.env.example
+
+# ── Temporary / backup files ─────────────────────────────────────────────
+/tmp/
+*.tmp
+*.temp
+*.pid
+
+# ── dpc agent logs ───────────────────────────────────────────────────────
+dpc.log
+
+# ── Coverage reports ─────────────────────────────────────────────────────
+*.gcda
+*.gcno
+*.gcov
+lcov.info
+coverage/