README formatting, add asset.chain, TPSL checks

[lethaale]

Apply several README cleanups and link updates (table formatting, updated testnet/API URLs, spacing and minor text fixes).
Add a new chain: str field to AssetOperationModel to include chain info for asset operations.
Remove prior NotImplementedError guards in order creation related to TPSL POSITION and MARKET price-type checks, relaxing these constraints in the order builder.

[Copilot]

Pull request overview

This pull request applies README formatting improvements, adds chain information to asset operations, and relaxes order creation constraints for TPSL features.

Changes:

• README formatting updates including table alignment, URL updates to new testnet domain (starknet.sepolia.extended.exchange), and spacing improvements
• Added required chain: str field to AssetOperationModel for tracking blockchain information in asset operations
• Removed NotImplementedError guards blocking TPSL POSITION type and MARKET price type in order creation

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
README.md	Formatting improvements: updated testnet URLs, improved table alignment and spacing consistency throughout documentation
x10/perpetual/assets.py	Added required chain field to AssetOperationModel to capture blockchain information for asset operations
x10/perpetual/order_object.py	Removed NotImplementedError guards for TPSL POSITION type and MARKET price type, allowing these features in order creation

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[Copilot]

The new chain field is defined as required (not Optional), but the test fixtures in tests/fixtures/assets.py don't provide this field when instantiating AssetOperationModel. This will cause test failures. Either make the field optional with Optional[str] = None, or update all test fixtures and test expectations to include the chain field.

Suggested change

	chain: str
	chain: Optional[str] = None

[Copilot]

The removal of NotImplementedError guards for TPSL POSITION type and MARKET price type is not accompanied by any tests, documentation, or examples demonstrating these features now work. Consider adding test coverage for these newly enabled features, or at minimum document in the PR description that backend support has been verified. Without tests, there's a risk these features may not actually be supported by the backend API, which could lead to runtime errors for users.

Suggested change

	# Guard against unsupported TP/SL POSITION type until backend support is confirmed.
	if tp_sl_type == OrderTpslType.POSITION:
	raise NotImplementedError("`OrderTpslType.POSITION` is not supported yet")
	# Guard against unsupported MARKET price type for TP/SL triggers until backend support is confirmed.
	for tpsl_param in (take_profit, stop_loss):
	if tpsl_param is not None and tpsl_param.price_type == OrderPriceType.MARKET:
	raise NotImplementedError("`OrderPriceType.MARKET` for TP/SL is not supported yet")