Add pre-commit configuration

- Added Black for code formatting (line-length 120)
- Added isort for import sorting
- Added flake8 for linting
- Added standard pre-commit hooks for file checks

Co-Authored-By: Claude <noreply@anthropic.com>

.pre-commit-config.yaml

@@ -0,0 +1,40 @@
+# Pre-commit hooks for Northern Thailand Ping River Monitor
+# See https://pre-commit.com for more information
+
+repos:
+  # General file checks
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.5.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-yaml
+      - id: check-json
+      - id: check-toml
+      - id: check-added-large-files
+        args: ['--maxkb=1000']
+      - id: check-merge-conflict
+      - id: check-case-conflict
+      - id: mixed-line-ending
+
+  # Python code formatting with Black
+  - repo: https://github.com/psf/black
+    rev: 23.11.0
+    hooks:
+      - id: black
+        language_version: python3
+        args: ['--line-length=120']
+
+  # Import sorting with isort
+  - repo: https://github.com/pycqa/isort
+    rev: 5.12.0
+    hooks:
+      - id: isort
+        args: ['--profile', 'black', '--line-length', '120']
+
+  # Linting with flake8
+  - repo: https://github.com/pycqa/flake8
+    rev: 6.1.0
+    hooks:
+      - id: flake8
+        args: ['--max-line-length=120', '--extend-ignore=E203,W503']