feat: memory.ingestMedia() — multimodal ingestion (v0.5.0)

[rrader26]

Adds memory.ingestMedia() — the client half of multimodal ingestion (engine PR #58, shell PR #56).

const res = await tf.memory.ingestMedia({
  media: fs.readFileSync('receipt.png'),   // Uint8Array | Buffer | base64 string
  mimeType: 'image/png',
  source: 'receipt.png',
})
res.extractedText   // what the model read
res.saved           // MemoryItem[] created from it
res.modality        // 'image' | 'audio' | 'document'
res.blobUri         // stored-media location (if retained)

• IngestMediaRequest/IngestMediaResult types.
• MemoryResource.ingestMedia — reuses the cross-platform toBase64, POSTs to /memory/media.
• Exported from the barrel; v0.4.1 → v0.5.0 (new feature).

Verified: tsc --noEmit clean, tsup build clean, check:proto passes (ingestMedia now covered, 42/47 RPCs). Republish to npm after merge.

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