Initial commit: Clean Mold Cost Calculator application

- Flask-based mold cost calculation application
- PostgreSQL database with SQLAlchemy ORM
- Docker/Podman containerization
- Comprehensive documentation in docs/
- Clean, organized codebase without obsolete files
- Production-ready deployment configuration
- Enhanced pytest configuration with coverage reporting
- Master/Development branch structure

app/templates/errors/400.html

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+{% extends "base.html" %}
+
+{% block title %}Bad Request - MoldCost Pro{% endblock %}
+
+{% block content %}
+<div class="container mt-5">
+    <div class="text-center">
+        <h1 class="display-1">400</h1>
+        <h2 class="mb-4">Bad Request</h2>
+        <p class="lead">The request was invalid or cannot be served.</p>
+        <a href="{{ url_for('main.home') }}" class="btn btn-primary">Return Home</a>
+    </div>
+</div>
+{% endblock %} 

app/templates/errors/403.html

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+{% extends "base.html" %}
+
+{% block title %}Forbidden - MoldCost Pro{% endblock %}
+
+{% block content %}
+<div class="container mt-5">
+    <div class="text-center">
+        <h1 class="display-1">403</h1>
+        <h2 class="mb-4">Access Forbidden</h2>
+        <p class="lead">You don't have permission to access this resource.</p>
+        <a href="{{ url_for('main.home') }}" class="btn btn-primary">Return Home</a>
+    </div>
+</div>
+{% endblock %} 

app/templates/errors/404.html

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+{% extends "base.html" %}
+
+{% block title %}Not Found - MoldCost Pro{% endblock %}
+
+{% block content %}
+<div class="container mt-5">
+    <div class="text-center">
+        <h1 class="display-1">404</h1>
+        <h2 class="mb-4">Page Not Found</h2>
+        <p class="lead">The page you're looking for doesn't exist.</p>
+        <a href="{{ url_for('main.home') }}" class="btn btn-primary">Return Home</a>
+    </div>
+</div>
+{% endblock %} 

app/templates/errors/409.html

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+{% extends "base.html" %}
+
+{% block content %}
+<div class="container mt-5">
+    <div class="row justify-content-center">
+        <div class="col-md-8">
+            <div class="card">
+                <div class="card-header bg-warning text-white">
+                    <h4 class="mb-0">Conflict</h4>
+                </div>
+                <div class="card-body">
+                    <h5 class="card-title">Data Constraint Error</h5>
+                    <p class="card-text">{{ message }}</p>
+                    <p class="card-text">This error typically occurs when trying to create a duplicate record or violate a data constraint.</p>
+                    <p class="card-text">Please check your input and try again.</p>
+                    <a href="{{ url_for('main.index') }}" class="btn btn-primary">Return to Home</a>
+                </div>
+            </div>
+        </div>
+    </div>
+</div>
+{% endblock %} 

app/templates/errors/500.html

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+{% extends "base.html" %}
+
+{% block title %}Server Error - MoldCost Pro{% endblock %}
+
+{% block content %}
+<div class="container mt-5">
+    <div class="text-center">
+        <h1 class="display-1">500</h1>
+        <h2 class="mb-4">Server Error</h2>
+        <p class="lead">Something went wrong on our end. Please try again later.</p>
+        <a href="{{ url_for('main.home') }}" class="btn btn-primary">Return Home</a>
+    </div>
+</div>
+{% endblock %} 

app/templates/errors/503.html

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+{% extends "base.html" %}
+
+{% block content %}
+<div class="container mt-5">
+    <div class="row justify-content-center">
+        <div class="col-md-8">
+            <div class="card">
+                <div class="card-header bg-warning text-white">
+                    <h4 class="mb-0">Service Temporarily Unavailable</h4>
+                </div>
+                <div class="card-body">
+                    <h5 class="card-title">Database Connection Error</h5>
+                    <p class="card-text">{{ message }}</p>
+                    <p class="card-text">Our technical team has been notified and is working to resolve this issue.</p>
+                    <p class="card-text">Please try again in a few minutes.</p>
+                    <a href="{{ url_for('main.index') }}" class="btn btn-primary">Return to Home</a>
+                </div>
+            </div>
+        </div>
+    </div>
+</div>
+{% endblock %}