Add named parameter support for SQL queries

New Feature: Named SQL Parameters
- Supports both positional (?) and named (:name) parameters
- Named parameters are order-independent and more readable
- Syntax: sqlite_param :param_name $variable

Implementation:
- Updated sqlite_param directive to accept 1 or 2 arguments
- ModuleConfig.query_params now stores (name, variable) pairs
- execute_query() detects named vs positional parameters
- Extracted row_to_map closure to avoid type conflicts
- Named params use rusqlite named parameter binding

Examples (Port 8082):
- Book detail: WHERE id = :book_id
- Genre filter: WHERE genre = :genre_name
- Year range: WHERE year >= :min_year AND year <= :max_year
- Title search: WHERE title LIKE '%' || :search_term || '%'
- Rating filter: WHERE rating >= :min_rating

Benefits of Named Parameters:
- Order-independent: params can be in any order in config
- Self-documenting: :book_id is clearer than first ?
- Maintainable: can add/remove params without reordering
- Recommended for all but simplest queries

Configuration:
- conf/book_named_params.conf: Complete named params example
- start_named_params.sh: Quick start script for port 8082

Documentation:
- Added named vs positional comparison in README_PARAMETERS.md
- Updated README.md with named parameter examples
- Documented both syntaxes in directive reference

All examples tested and working with both parameter styles.

README.md

@@ -48,17 +48,29 @@ A full-featured catalog with category browsing, global templates, and responsive
 
 **See:** `conf/book_catalog.conf` and `README_BOOK_CATALOG.md`
 
-### Example 2: Parameterized Queries (Port 8081)
+### Example 2: Positional Parameters (Port 8081)
 
-Demonstrates dynamic SQL queries with nginx variables.
+Demonstrates dynamic SQL queries with positional parameters.
 
 **Features:**
-- Book detail pages by ID
-- Genre filtering with query parameters
-- Year range searches with multiple parameters
-- Safe prepared statement parameter binding
+- Query parameters with `?` placeholders
+- Multiple positional parameters
+- Safe prepared statement binding
 
-**See:** `conf/book_detail.conf` and `README_PARAMETERS.md`
+**See:** `conf/book_detail.conf`
+
+### Example 3: Named Parameters (Port 8082) - Recommended
+
+Demonstrates named SQL parameters for better readability.
+
+**Features:**
+- Named parameters with `:name` syntax
+- Order-independent parameter binding
+- Title search with LIKE operator
+- Rating filtering
+- More maintainable configuration
+
+**See:** `conf/book_named_params.conf` and `README_PARAMETERS.md`
 
 ## Configuration Directives
 
@@ -85,9 +97,14 @@ Specify the Handlebars template file (relative to location path).
 ### `sqlite_param`
 Add a parameter to the SQL query (can be used multiple times).
 
-**Syntax:** `sqlite_param $variable_or_value;`  
+**Syntax:**  
+- Positional: `sqlite_param $variable_or_value;`  
+- Named: `sqlite_param :param_name $variable_or_value;`
+
 **Context:** `location`  
-**Notes:** Order matches `?` placeholders in query
+**Notes:**  
+- Positional parameters match `?` placeholders in order
+- Named parameters match `:name` placeholders by name (recommended)
 
 ### `sqlite_global_templates`
 Set a directory for global template files (partials, layouts).
@@ -112,13 +129,22 @@ http {
             sqlite_template "list.hbs";
         }
         
-        # Parameterized query
+        # Parameterized query with named parameter (recommended)
         location = /book {
             sqlite_db "catalog.db";
-            sqlite_query "SELECT * FROM books WHERE id = ?";
-            sqlite_param $arg_id;
+            sqlite_query "SELECT * FROM books WHERE id = :book_id";
+            sqlite_param :book_id $arg_id;
             sqlite_template "detail.hbs";
         }
+        
+        # Positional parameters also supported
+        location = /search {
+            sqlite_db "catalog.db";
+            sqlite_query "SELECT * FROM books WHERE year >= ? AND year <= ?";
+            sqlite_param $arg_min;  # First ?
+            sqlite_param $arg_max;  # Second ?
+            sqlite_template "list.hbs";
+        }
     }
 }
 ```