Implement proper quote handling for PostgreSQL connection strings

[Copilot]

The custom connection string parser did not handle quoted values, breaking passwords with spaces or special characters.

Changes

• Implement custom parser with quote support: Creates an implementation-agnostic parser that handles quoted values, escaped characters, and all sqlpp23 connection_config parameters without using PostgreSQL-specific types
• Maintain sqlpp23 abstraction: Uses only sqlpp23's connection_config interface, preserving the implementation-agnostic design principle
• Implement PostgreSQL-compliant boolean parsing: Accepts true/false, on/off, yes/no, 1/0 (case-insensitive)
• Improve error reporting: Specific messages for invalid values with parameter context

Example

Before:

// This would fail to parse correctly
db = Database("password=my pass word");  // Broken: treats "my" as password

After:

// Now handles quoted values properly
db = Database("password='my pass word'");
db = Database("dbname='test-db' password='p@ss w0rd!'");

Documentation

Updated docs/README.md with connection string format reference and examples showing proper quoting.

Design Note

The implementation uses a custom parser rather than libpq's PQconninfoParse() to maintain the implementation-agnostic interface provided by sqlpp23. This ensures the codebase doesn't become tightly coupled to PostgreSQL-specific types while still providing full quote handling support.

[!WARNING]

Original prompt

---

This section details on the original issue you should resolve

<filter_complete></filter_complete>

<issue_title>Implement proper quote handling for full PostgreSQL connection string support</issue_title>
<issue_description>See Database.cpp:

        // Parse connection string (PostgreSQL libpq format)
        // Supported format: "key1=value1 key2=value2 ..."
        // Supported keys: host, dbname, user, password, port
        // 
        // NOTE: This parser does not handle quoted values (e.g., password='my pass').
        // Values containing spaces or special characters will be incorrectly parsed.
        // This limitation is acceptable for the keys currently parsed (host, dbname, 
        // user, password, port) as spaces are unlikely to appear in these values.
        // TODO: Create GitHub issue to implement proper quote handling for full 
        // PostgreSQL connection string support (see libpq documentation).
```</issue_description>

<agent_instructions>The quoted lines were from before the introduction of sqlpp23 in this code base. Assess if the quote handling is still needed or if this is already done by sqlpp23.</agent_instructions>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes Implement proper quote handling for full PostgreSQL connection string support #8

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Implement proper quote handling for full PostgreSQL connection string support</issue_title>
<issue_description>See Database.cpp:

        // Parse connection string (PostgreSQL libpq format)
        // Supported format: "key1=value1 key2=value2 ..."
        // Supported keys: host, dbname, user, password, port
        // 
        // NOTE: This parser does not handle quoted values (e.g., password='my pass').
        // Values containing spaces or special characters will be incorrectly parsed.
        // This limitation is acceptable for the keys currently parsed (host, dbname, 
        // user, password, port) as spaces are unlikely to appear in these values.
        // TODO: Create GitHub issue to implement proper quote handling for full 
        // PostgreSQL connection string support (see libpq documentation).
```</issue_description>

<agent_instructions>The quoted lines were from before the introduction of sqlpp23 in this code base. Assess if the quote handling is still needed or if this is already done by sqlpp23.</agent_instructions>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes Implement proper quote handling for full PostgreSQL connection string support #8

---

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[wdconinc]

@copilot The changes to Database.cpp tie the interface much too close to postgresql. We use sqlpp23 to have an intermediate, implementation-agnostic interface. Using PQconinfoOption violates this benefit. Re-assess this and find a solution for input validation and quoting that maintains the implementation-agnostic sqlpp23 interface.

[Copilot]

@copilot The changes to Database.cpp tie the interface much too close to postgresql. We use sqlpp23 to have an intermediate, implementation-agnostic interface. Using PQconinfoOption violates this be...

Reverted the PostgreSQL-specific implementation and replaced it with a custom parser that maintains the implementation-agnostic sqlpp23 interface. The new implementation properly handles quoted values and escaped characters without using PQconninfoOption or any PostgreSQL-specific types. Commit: e7dd942