Add Smart Identifier Quoting for PostgreSQL Compatibility

[screenfluent]

Add Smart Identifier Quoting for PostgreSQL Compatibility

Problem

pgschema currently strips quotes from identifiers, causing issues with:

• Reserved words (e.g., user, order, group)
• CamelCase/MixedCase identifiers (e.g., userId, createdAt)
• Modern ORMs and auth libraries (Better Auth, Prisma, Drizzle)

PostgreSQL lowercases unquoted identifiers, so userId becomes userid, breaking compatibility with libraries expecting exact case.

Solution

This PR adds intelligent identifier quoting that preserves quotes when needed:

• Reserved PostgreSQL keywords → quoted
• Mixed case identifiers → quoted
• Special characters → quoted
• Simple lowercase → unquoted (no change)

Changes

• Added identifier_quote.go with quoting logic
• Updated getTableNameWithSchema() and qualifyEntityName() to use quoting
• Modified table/column generation to preserve case
• Added comprehensive tests

Impact

• Better Auth users can use pgschema without field mapping
• Prisma/Drizzle schemas work out-of-the-box
• Backwards compatible - only quotes when necessary

Example

Before:

-- Input schema
CREATE TABLE "user" (
    "userId" TEXT,
    "createdAt" TIMESTAMP
);

-- pgschema output (broken)
CREATE TABLE user (  -- ERROR: reserved word
    userid TEXT,      -- wrong case
    createdat TIMESTAMP -- wrong case
);

After:

-- pgschema output (fixed)
CREATE TABLE "user" (
    "userId" TEXT,
    "createdAt" TIMESTAMP
);

Testing

• Added unit tests for quoting logic
• Tested with Better Auth schema
• Backwards compatible with existing schemas

Fixes compatibility with: Better Auth, Supabase Auth, Lucia Auth, Prisma, Drizzle, TypeORM

[tianzhou]

LGTM. Thanks for the PR!