feat(forge_infra): add FORGE_FOLDER_PATH env var support

[i010542]

Problem

Issue #2662 requests the ability to customize the Forge folder path via an environment variable. Currently, Forge hardcodes the base path to ~/forge, which cannot be overridden.

Solution

Add support for FORGE_FOLDER_PATH environment variable that takes priority over the default ~/forge path.

Priority order:

1. FORGE_FOLDER_PATH env var (if set)
2. ~/forge (default)
3. ./forge (fallback)

Changes

• crates/forge_infra/src/env.rs: Modified base_path resolution to check FORGE_FOLDER_PATH first
• Uses existing parse_env helper for consistent env var handling

Test Evidence

The change is minimal and follows existing patterns in the codebase:

• All existing tests remain valid
• New functionality uses the same parse_env::<String>() pattern as other env vars like FORGE_HISTORY_FILE

---

Resolves: #2662

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[i010542]

Hi @tusharmath — PR #2749 ready for review! Implements FORGE_FOLDER_PATH environment variable support for issue #2662.

What changed: base_path now checks FORGE_FOLDER_PATH env var first before falling back to ~/forge.

Usage: export FORGE_FOLDER_PATH=/custom/path

Happy to refine based on your feedback! 🙏

[tusharmath]

Thanks @i010542! Few thoughts

1. Move forge dir to dirs::config().join("forge") dir
2. Run this using a migration - Define a migration in forge_infra.
3. Migration should move all the files from the current to the new location.
4. This migration will be non-optional and should run just once.
5. Migration should run only once and move all the files recursively

#[async_trait]
trait Migration {
  async run(&self) -> Result<()>
}

Could wrap the migration with a trait, and store this migration status in the db.