Fix typo: rename ActionMetadata.funtion_name → function_name (proto, backend, SDK stubs)

## Summary

There's a typo in one of our protobuf fields: `funtion_name` should be `function_name` (missing the **c**). It lives on the `ActionMetadata` message and flows through the generated code in every language, the Go backend, and the published `flyteidl2` package that the Python SDK depends on.

> This spans **two repos**: most of the work is in [`flyteorg/flyte`](https://github.com/flyteorg/flyte) (Parts 1–3), plus a small follow-up in [`flyteorg/flyte-sdk`](https://github.com/flyteorg/flyte-sdk) (Part 4). It's totally fine to do Part 4 as a second PR — see the note there.

## Background

The field is defined here:

`flyteidl2/workflow/run_definition.proto` (around line 188)
```proto
message ActionMetadata {
...
// Function name
string funtion_name = 13; // 👈 typo: "funtion" → "function"
...
}
```

The `= 13` is the field's **wire number** — we keep it as `13` so this change is fully backward-compatible on the wire. We're only fixing the human-readable name.

## What needs to change

### 1. Fix the proto (the only file you edit by hand for the IDL) — repo: `flyteorg/flyte`

In `flyteidl2/workflow/run_definition.proto`:
```diff
- string funtion_name = 13;
+ string function_name = 13;
```
Leave the `= 13` and the `// Function name` comment as-is.

### 2. Regenerate the code stubs (proto → Go/Python/TypeScript/Rust) — repo: `flyteorg/flyte`

The files under `gen/` are **generated** — don't edit them by hand. Regenerate them:

```bash
make buf
```

This rewrites the generated stubs, including:
- `gen/go/flyteidl2/workflow/run_definition.pb.go` — Go field `FuntionName` → `FunctionName`, getter `GetFuntionName()` → `GetFunctionName()`
- `gen/python/flyteidl2/workflow/run_definition_pb2.pyi` (+ `_pb2.py`) — Python attr `funtion_name` → `function_name` (this is what gets published as the `flyteidl2` package)
- `gen/ts/flyteidl2/workflow/run_definition_pb.ts` — TypeScript `funtionName` → `functionName`
- `gen/rust/src/flyteidl2.workflow.rs` — Rust `funtion_name` → `function_name`

> 💡 **Don't have the full toolchain (buf/go/uv/cargo) installed?** No problem — open your PR with just the proto change, then comment **`/regen`** on the PR and CI will regenerate and commit the stubs for you.

### 3. Fix the backend (Go) references — repo: `flyteorg/flyte`

Two hand-written spots use the old generated name. In `runs/service/run_service.go`:

```diff
- FuntionName: action.FunctionName,
+ FunctionName: action.FunctionName,
```
(around line 1534, inside `actionMetadataFromModel`)

```diff
- metadata.FuntionName = action.FunctionName
+ metadata.FunctionName = action.FunctionName
```
(around line 1832)

Note `action.FunctionName` (the DB model side) is **already** spelled correctly — you're only renaming the generated proto symbol on the left.

### 4. Update the Python SDK — repo: [`flyteorg/flyte-sdk`](https://github.com/flyteorg/flyte-sdk)

`flyte-sdk` doesn't vendor the stubs — it depends on the **published `flyteidl2` package** (see `flyteidl2==2.0.x` in its `pyproject.toml`) and imports `from flyteidl2.workflow import run_definition_pb2`.

So, once the change above is merged **and a new `flyteidl2` package is released**:

1. Bump the `flyteidl2==` pin in `flyte-sdk`'s `pyproject.toml` to the version that contains the fix.
2. Search the SDK for any reference to the old name and update it:
```bash
grep -rn "funtion_name\|funtionName" . # in the flyte-sdk repo
```
(As of now there are **no** references, so this is mostly a dependency bump + a sanity grep — but please double-check, since `src/flyte/remote/_condition.py` imports `run_definition_pb2`.)

> ⏳ **Ordering:** Part 4 depends on a `flyteidl2` release, which happens after the `flyteorg/flyte` PR merges. Open it as a **separate follow-up PR** against `flyte-sdk`. If you only want to tackle the `flyteorg/flyte` side, that's a complete and valuable contribution on its own — just leave a comment so someone can pick up the SDK bump.

## How to verify you're done (the `flyteorg/flyte` side)

```bash
# 1. No occurrences of the typo anywhere:
grep -rn "funtion" . | grep -v ".git/" # should print nothing

# 2. Backend compiles:
go build ./runs/...
```

CI's `check-generate` job also runs `make buf` and fails if the generated files weren't updated — so make sure the regenerated `gen/` files are committed.

## Acceptance criteria

**In `flyteorg/flyte`:**
- [ ] `funtion_name` → `function_name` in `flyteidl2/workflow/run_definition.proto` (field number stays `13`)
- [ ] All `gen/` stubs regenerated (Go, Python, TypeScript, Rust) and committed
- [ ] Both references in `runs/service/run_service.go` updated to `FunctionName`
- [ ] `grep -rn "funtion" .` returns nothing; `go build ./runs/...` passes
- [ ] Commits are signed off (`git commit -s`)

**In `flyteorg/flyte-sdk` (follow-up, after a new `flyteidl2` release):**
- [ ] `flyteidl2==` pin bumped to the version containing the fix
- [ ] `grep -rn "funtion_name\|funtionName" .` returns nothing

## Pointers for first-time contributors

- Contributing guide: see `CONTRIBUTING.md` in the repo root.
- The PR template will ask you to pick a changelog label — use **changed**.
- Stuck on anything? Comment on this issue and a maintainer will help. 🙌