feat(pgpm): add interactive prompts for export flow

[pyramation]

Summary

Adds interactive prompts to the pgpm export command for two scenarios:

1. Module overwrite confirmation: When exporting to a module that already exists, prompts the user with "Module exists. Overwrite? [y/N]" before deleting deploy/revert/verify directories
2. Missing module auto-install: Detects which pgpm modules from the required extensions list are missing from the workspace and offers to install them automatically

The prompter parameter is now threaded through exportMigrations → exportMigrationsToDisk → preparePackage and promptAndInstallMissingModules. When no prompter is provided (non-interactive mode), the existing behavior is preserved.

Code Organization

• PGPM_MODULE_MAP and getMissingInstallableModules() extracted to pgpm/core/src/modules/modules.ts for reusability
• DB_REQUIRED_EXTENSIONS and SERVICE_REQUIRED_EXTENSIONS constants hoisted to top of export-migrations.ts
• Uses getInstalledModules() for accurate detection of installed npm packages

Updates since last revision

• Moved PGPM_MODULE_MAP and detection logic to modules/modules.ts (more generic location near module installation code)
• Added MissingModule interface for type safety
• Hoisted extension constants (DB_REQUIRED_EXTENSIONS, SERVICE_REQUIRED_EXTENSIONS) per code review feedback
• Renamed checkAndInstallMissingModules → promptAndInstallMissingModules for clarity
• Switched from getModuleMap() to getInstalledModules() for more accurate installed module detection

Review & Testing Checklist for Human

• Verify PGPM_MODULE_MAP accuracy: The mapping was built by inspecting the pgpm-modules repo. Confirm all 11 entries are correct and no modules are missing
• Test project.getInstalledModules() return value: The code compares against installed array which should contain npm package names (e.g., @pgpm/base32) - verify this matches actual behavior
• Test project.installModules() with npm package names: The code passes @pgpm/base32 style names - verify this is the expected format
• Manual E2E test: Run pgpm export on a database with existing modules and verify:
  • Overwrite prompt appears when module exists
  • Missing module detection works correctly
  • Module installation succeeds when confirmed

Notes

• No unit tests were added for the new functionality
• When user declines overwrite, an error is thrown (Export cancelled: Module "X" already exists.) - consider if this is the desired UX

Requested by: Dan Lynch (@pyramation)
Devin session: https://app.devin.ai/sessions/7e7813472a0643aa88ccb509b288050a

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