feat(meta): Add pricing and capabilities configuration

[mayankjain-panw]

Summary

Adds pricing and model capabilities configuration for Meta Model API (Muse Spark models).

Changes

• pricing/meta.json: Token pricing for all 3 models + default zero-cost baseline
• general/meta.json: Model parameters and capability declarations

Pricing source

From Meta docs (pricing-rate-limits):

Model	Input ($/1M)	Output ($/1M)	Cached ($/1M)
muse-spark-1.1	$1.25	$4.25	$0.15
muse-spark-1.2	$1.25	$4.25	$0.15
muse-spark-1.2-contributor	$0.10	$0.20	$0.002

Conversion: price_value = dollars_per_million / 10_000 (verified against x-ai and anthropic entries).

Capabilities

• Context window: 1,048,576 tokens
• Supported: chat, tools, image, video
• stop parameter intentionally omitted (Meta rejects it on reasoning models)

Validation

Both JSON files pass JSON.parse() validation.