Fix --file/--body aliasing in pc vector upsert (#64)

## Problem
@bradumbaugh reported an issue with the aliasing in the `pc vector
upsert` command. `--file` and `--body` flags are meant to be aliases,
but `--file` is configured as required making `--body` unusable due to
cobra error'ing when `--file` is not passed.

## Solution
Make sure --file is not configured as a required flag to vector upsert
since --body is an alias, add custom validation / error handling for the
empty file/body case.

Additionally, I cleaned up a `.cache` folder that was incorrectly
committed to source previously, along with removing the
claude-code-review workflows from the repo. We've been using cursorbot
generally, and I'll get this repo setup with that in a follow-up PR.

### Before
```
./dist/pc_darwin_arm64_v8.0/pc index vector upsert --index-name test-cps --body /Users/austin/workspace/go-pinecone-consumer/dense_dim_3_x4.json
Error: required flag(s) "file" not set
Usage:
  pc index vector upsert [flags]

Examples:
  $ pc index vector upsert --index-name my-index --namespace my-namespace --body ./vectors.json
  $ pc index vector upsert --index-name my-index --namespace my-namespace --body ./vectors.jsonl
  $ cat payload.json | pc index vector upsert --index-name my-index --namespace my-namespace --body -

Flags:
  -b, --batch-size int      size of batches to upsert (default: 500) (default 500)
      --body string         alias for --file
      --file string         request body JSON or JSONL (inline, ./path.json[l], or '-' for stdin; only one argument may use stdin)
  -h, --help                help for upsert
  -n, --index-name string   name of index to upsert into
  -j, --json                output as JSON
      --namespace string    namespace to upsert into (default "__default__")

Global Flags:
  -q, --quiet              suppress output
      --timeout duration   timeout for commands, defaults to 60s (0 to disable) (default 1m0s)
```

###After
```
./dist/pc_darwin_arm64_v8.0/pc index vector upsert --index-name test-cps --body /Users/austin/workspace/go-pinecone-consumer/dense_dim_3_x4.json
[SUCCESS] Upserted 4 vectors into namespace __default__ (batch 1 of 1)
```

## Type of Change
- [X] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] This change requires a documentation update
- [ ] Infrastructure change (CI configs, etc)
- [ ] Non-code change (docs, etc)
- [ ] None of the above: (explain here)

## Test Plan
Test corrected flow by calling `pc index vector upsert --index-name
my-index --body my-file.json` and observe no errors.


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Author: austin-denoble