feat(llm): add CLI subcommands moagan probe top_p + moagan probe top_k (D7)

## Goal

Add the CLI verbs `moagan probe top_p` and `moagan probe top_k` per #900 D7. Mirror the existing `moagan probe temperature` and `moagan probe max_tokens` verbs. Both verbs run the auto-probe, persist the result to `/top_p_auto.toml` and `/top_k_auto.toml`, and accept `--persist-min` / `--persist-union` flags (D10: fixed safe set — these are now permanent code, not user-configurable).

## Why now

#12 lands the underlying `TopPTable` / `TopKTable` infrastructure. This issue exposes them via the CLI, completing the two-plane naming contract from #900 D7 (wire field `top_p` / `top_k`; CLI verb `moagan probe top_p` / `moagan probe top_k`; sidecar file `top_p_auto.toml` / `top_k_auto.toml`).

## Scope

**In scope:**
- `src/cli/probe.rs` (already has `ProbeCmd` enum at `:65-84`): add two new variants:
- `ProbeCmd::TopP(ProbeTopPCmd)`
- `ProbeCmd::TopK(ProbeTopKCmd)`
- Each variant mirrors the existing `ProbeMaxTokensCmd` / `ProbeTemperatureCmd` shape (`:87-157`):
- `--provider PROVIDER:MODEL` (required, repeatable).
- `--persist-min` (for `top_p` / `top_k` — pins the operator cap to the minimum accepted value).
- `--batch-size N` (for `top_p` — defaults to the per-verb batch size constant).
- `--dry-run` (don't persist to disk).
- `dispatch(cmd: &ProbeCmd)` at `src/cli/probe.rs:160-166`: add the two new arms.
- `dispatch_top_p` / `dispatch_top_k` functions (mirror `dispatch_temperature` at `:353-502`):
- Build the underlying `LlmClient` via `client::dispatcher::build_client` (issue #4).
- Wrap in `LlmClientProbeTransport` (introduced in #7).
- Run the probe via `TopPTable::probe_and_store(...)` / `TopKTable::probe_and_store(...)`.
- On `--persist-min`, call `TopPTable::set_operator_cap(...)` / `TopKTable::set_operator_cap(...)`.
- Unit tests at `src/cli/probe.rs::tests` that pin the new CLI verbs.
- Update `src/cli/probe.rs::tests::build_provider_for_spec_*` to assert the two new verbs route through the dispatcher.

**Out of scope:**
- The underlying `TopPTable` / `TopKTable` infrastructure — issue #12.
- Cascade absorption (D9) / audit-hash kill (D8) — issue #14.
- Legacy `Provider` deletion — issue #15.

## Approach

### 1. CLI verb shape

```rust
#[derive(Debug, Clone, clap::Args)]
pub struct ProbeTopPCmd {
#[arg(long = "provider", value_name = "PROVIDER:MODEL", required = true, num_args = 1..)]
pub providers: Vec,
#[arg(long, default_value_t = false)]
pub persist_min: bool,
#[arg(long, default_value_t = TOP_P_PROBE_BATCH_SIZE)]
pub batch_size: usize,
#[arg(long, default_value_t = false)]
pub dry_run: bool,
}

#[derive(Debug, Clone, clap::Args)]
pub struct ProbeTopKCmd {
#[arg(long = "provider", value_name = "PROVIDER:MODEL", required = true, num_args = 1..)]
pub providers: Vec,
#[arg(long, default_value_t = false)]
pub persist_min: bool,
#[arg(long, default_value_t = false)]
pub dry_run: bool,
}
```

(`top_k` doesn't take `--batch-size` because the algorithm walks powers of 2 — the batch is fixed.)

### 2. `dispatch_top_p` function

Mirror `dispatch_temperature` at `src/cli/probe.rs:353-502`:

```rust
pub async fn dispatch_top_p(cmd: &ProbeTopPCmd) -> Result {
// 1. Resolve each `provider:model` pair via `cfg.providers_by_section`.
// 2. Build an LlmClient via `client::dispatcher::build_client` (issue #4).
// 3. Wrap in `LlmClientProbeTransport` (issue #7).
// 4. Load `TopPTable::from_home(&home, floor, save)`.
// 5. Run `TopPTable::probe_and_store(transport, ...)` with cmd.batch_size.
// 6. On `--persist-min`, call `TopPTable::set_operator_cap(...)`.
// 7. Print the discovered top_p set + operator cap to stdout.
// 8. Exit 0 on success, 1 on probe failure.
}
```

### 3. Unit tests

- `dispatch_top_p_accepts_provider` — wiremock returns `200` for `top_p=0.5`, `400` for `top_p=0.55`. Probe returns `0.5`.
- `dispatch_top_p_persist_min_writes_cap` — `--persist-min` → sidecar has `operator_caps..auto = false, .top_p = 0.5`.
- `dispatch_top_p_dry_run_does_not_persist` — `--dry-run` → sidecar unchanged.
- `dispatch_top_k_walks_powers_of_2` — wiremock accepts `1, 2, 4, 8, 16`, rejects `32`. Probe returns `16`.
- `dispatch_top_k_persist_min_writes_cap` — same as top_p.

## Acceptance criteria

- [ ] `cargo build --release --all-features` succeeds with **zero warnings**.
- [ ] `make fmt-check guard-deps lint build test-ci` green.
- [ ] `moagan probe top_p --help` and `moagan probe top_k --help` print the new args.
- [ ] `moagan probe top_p --provider mock:mock-model --dry-run` runs without error.
- [ ] `moagan probe top_k --provider mock:mock-model --dry-run` runs without error.
- [ ] `moagan probe top_p --provider mock:mock-model --persist-min` writes `/top_p_auto.toml` with `operator_caps.mock.mock-model.auto = false`.
- [ ] `moagan probe top_k --provider mock:mock-model --persist-min` writes `/top_k_auto.toml` similarly.
- [ ] New unit tests at `src/cli/probe.rs::tests` cover the 5 listed cases and pass.
- [ ] `cli-reference.md` documents the two new verbs.

## Merge order

```
#1-#11 (foundation + migration wave)
#12 (top_p_auto + top_k_auto infrastructure)
↓
#13 (this issue — CLI verbs)
↓
#14-#15 (cleanup wave)
```

## Validation

- `make fmt-check guard-deps lint build test-ci` green after the PR lands.
- 5 new unit tests pass.
- Manual: `moagan probe top_p --provider mock:mock-model --dry-run` and `moagan probe top_k --provider mock:mock-model --dry-run` run successfully.

## Version target

v0.18.0 (or v0.18.x patch — additive feature, no breaking changes). Per the operator's preference in the EPIC body comment, batching into v0.18.0 is the natural target.

## References

- [EPIC #847](https://github.com/airvzxf/moagan/issues/847) — the umbrella.
- [#900 D7, D10](https://github.com/airvzxf/moagan/issues/900) — `_auto` naming (D7), fixed safe set (D10).
- [`src/cli/probe.rs:65-166`](../blob/main/src/cli/probe.rs) — existing `ProbeCmd` enum and `dispatch` function.
- [`src/cli/probe.rs:353-502`](../blob/main/src/cli/probe.rs) — `dispatch_temperature` (mirrored by `dispatch_top_p`).
- [`src/cli/probe.rs:168-320`](../blob/main/src/cli/probe.rs) — `dispatch_max_tokens` (mirrored by `dispatch_top_k`).
- [Issue #4](../issues/921) (when created) — `client::dispatcher::build_client`.
- [Issue #7](../issues/924) (when created) — `LlmClientProbeTransport`.
- [Issue #12](../issues/929) (when created) — `TopPTable` / `TopKTable`.