[Bug]: "could not find vendor" error on v1.4.452 despite correct configuration in .env and config.yaml

### What happened?

Description:
After installing the latest version of Fabric (v1.4.452) via Go on Linux Mint,
the application fails to recognize configured AI vendors (specifically Ollama
and Gemini). Even after running fabric --setup and verifying that
~/.config/fabric/.env and config.yaml contain the correct values, the CLI
returns a "could not find vendor" error.

Environment:
- OS: Linux Mint 22.3 (Ubuntu 24.04 base)
- Go version: go1.22.2 linux/amd64 (switched to 1.25.10 during fabric
install)
- Fabric Version: v1.4.452
- Model Provider: Ollama (local)

Steps to Reproduce:
1. Install fabric via go install
github.com/danielmiessler/fabric/cmd/fabric@latest.
2. Run fabric --setup.
3. Configure Ollama (Vendor 26) with default settings.
4. Set default vendor to Ollama and default model to gemma3:4b.
5. Run: echo "test" | fabric --pattern summarize.

Expected Behavior:
Fabric should load the patterns and pipe the input to the configured Ollama
model.

Actual Behavior:

1 Requested Model =
2 Default Model = gemma3:4b
3 Default Vendor = Ollama.
4
5 could not find vendor
Note: Even manually specifying --vendor Ollama --model gemma3:4b results in no
AI vendors configured to read models from.

Workaround found:
Downgrading to version v1.4.322 resolved the issue immediately using the exact
same configuration files.
go install github.com/danielmiessler/fabric/cmd/fabric@v1.4.322

### Operating System

Linux - amd64

### OS Version

```shell
NAME="Linux Mint"
VERSION="22.3 (Zena)"
```

### How did you install Fabric?

From Source

### Version

```text
v1.4.322
```

### Relevant log output

```shell
1. Error when running a pattern:

1 Requested Model =
2 Default Model = gemma3:4b
3 Default Vendor = Ollama.
4
5 could not find vendor

2. Error when trying to list models:

1 no AI vendors configured to read models from

3. Error when trying to force vendor/model via flags:
1 no AI vendors configured to read models from. Please configure at least one
AI vendor

4. Go installation log (shows version requirement):

1 go: downloading github.com/danielmiessler/fabric v1.4.452
2 go: github.com/danielmiessler/fabric@v1.4.452 requires go >= 1.25.1;
switching to go1.25.10
3 go: downloading go1.25.10 (linux/amd64)

---

Why these logs are important:
* Logs 1 & 2 show that even though the variables are set, the application
logic isn't "seeing" them.
* Log 3 is the most critical because it shows that even the command-line
flags (which usually override everything) are failing, suggesting a deep
issue in the vendor initialization logic.
* Log 4 helps them see which specific Go toolchain was used for the build.
```

### Relevant screenshots (optional)

_No response_