DX-2963: add vector index commands and redis.vector namespace

[CahidArda]

Summary

Adds the new VECTOR.* commands (RED-769 / RED-962) behind a redis.vector namespace that mirrors redis.search, plus raw commands under pipeline.vector.*.

Usage

// create (or attach to) an index
const index = await redis.vector.createIndex({ name: "docs", dimension: 3, metric: "COSINE", existsOk: true }); // metric: COSINE | EUCLIDEAN | DOT
const same = redis.vector.index("docs"); // no round trip

// add — number[] (VALUES), Float32Array (BASE64-FP32), or a base64 FP32 blob from an embedding API
await index.add("doc-1", [0.1, 0.2, 0.3]);                         // 1 = inserted, 0 = overwritten
await index.add("doc-2", new Float32Array([0.3, 0.2, 0.1]));
await index.add("doc-3", { base64: embedding.data[0].embedding }); // openai encoding_format: "base64"

// query
const hits = await index.query({ vector: [0.1, 0.2, 0.3], topK: 5 });      // [{ id: "doc-1", score: 1 }, ...]
await index.query({ vector: queryVec, topK: 10, profile: "PRECISE" });      // FAST | BALANCED (default) | PRECISE

// read / manage
await index.get("doc-1");   // [0.1, 0.2, 0.3] | null
await index.count();        // 3
await index.info();         // { dimension: 3, metric: "COSINE" } | null
await index.delete("doc-1"); // 1 | 0
await index.drop();         // 1 | 0

// pipeline / multi
const [created, added, n] = await redis.multi()
  .vector.create("docs", { dimension: 3, metric: "DOT" })
  .vector.add("docs", "a", [1, 0, 0])
  .vector.count("docs")
  .exec();

Changes

- VectorCreate/Add/Get/Query/Del/Count/Info/DropCommand in pkg/commands/vector_*.ts; types, FP32→base64 encoding, deserializers and VectorIndex in pkg/commands/vector/
- Query ids stay strings (default deserialization would turn "123" into 123); scores/values coerced to numbers; VECTOR.INFO's flat array mapped to { dimension, metric }
- "vector" added to the auto-pipeline EXCLUDE_COMMANDS: the namespace exists on both Redis and Pipeline, so the proxy otherwise resolved redis.vector to the pipeline's and createIndex was undefined
- VectorIndex + types exported from platforms/nodejs; minor changeset

Testing

41 new tests (per command, encoding/deserialization, VectorIndex, pipeline/multi, Redis-level incl. the auto-pipeline proxy) against a locally built redis-server (master @ 15e7e53) — the hosted test DB doesn't have VECTOR.* yet, so CI will fail on these until it's upgraded. Full suite against that server: 950 pass / 0 fail; tsc/eslint/prettier/tsup clean.

[linear-code]

DX-2963