Fix DSN parsing error for special characters in passwords

[Copilot]

Problem

The database module was failing to parse DSN strings containing special characters in passwords. For example, this DSN would cause a parsing error:

postgresql://someuser:8jKwouNHdI!u6a?kx(UuQ-Bgm34P@some-dev-backend.cluster.us-east-1.rds.amazonaws.com/some_backend

The error occurred because Go's url.Parse() function treats special characters like !, ?, (, ) as URL syntax instead of literal password characters, resulting in:

parse "postgresql://someuser:8jKwouNHdI!u6a?kx(UuQ-Bgm34P@...": invalid port ":8jKwouNHdI!u6a" after host

Solution

Enhanced the DSN parsing logic in the database module to handle special characters in passwords by:

1. Preprocessing DSNs before parsing: Added preprocessDSNForParsing() function that intelligently identifies the password portion and URL-encodes special characters
2. Smart credential boundary detection: Uses the last @ symbol to separate credentials from host, handling cases where passwords contain @ symbols
3. Consistent handling across functions: Updated both extractEndpointFromDSN() and replaceDSNPassword() to use the same preprocessing approach

Changes

• Modified extractEndpointFromDSN() to preprocess DSNs with special characters
• Modified replaceDSNPassword() to handle special characters consistently
• Added preprocessDSNForParsing() helper function for URL-encoding password portions
• Added comprehensive test coverage for various special character scenarios

Test Coverage

Added extensive test cases covering:

• The exact DSN from the original issue
• Passwords with @ symbols, query parameters, and complex special characters
• Edge cases like multiple @ symbols and URL-like structures in passwords
• AWS IAM authentication scenarios with special character passwords

All existing tests continue to pass, ensuring no regressions.

Fixes #19.

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[codecov]

Codecov Report

Attention: Patch coverage is 78.18182% with 12 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
modules/database/aws_iam_auth.go	78.18%	8 Missing and 4 partials ⚠️

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[intel352]

@copilot Linter errors are showing up, please fix any linter errors and ensure tests are still passing.

[Copilot]

@copilot Linter errors are showing up, please fix any linter errors and ensure tests are still passing.

Fixed linter formatting errors (trailing whitespace) in aws_iam_auth.go and confirmed all tests are still passing. Commit: 118b615

[intel352]

@copilot

  Error: /home/runner/work/modular/modular/modules/database/dsn_special_chars_test.go:13:1: File is not properly formatted (gofmt)

[Copilot]

@copilot

...

Fixed gofmt formatting issues in dsn_special_chars_test.go by removing trailing whitespace and fixing struct field alignment. All tests are passing and the file now passes gofmt validation. Commit: 88e2363