Add single-file market maker bot example

[WGB5445]

Summary

Add a new single-file market maker bot example under examples/write/market_maker_bot.py.

What is included

• Inventory-skew quote computation around mid price
• Basic risk guards (max_inventory, max_margin_usage)
• Cancel-and-replace quoting cycle
• Dry-run mode for safe validation
• CLI flags for market, network, timing, and risk parameters

Why

This keeps the market-maker example self-contained and easy to run with the current Python SDK API surface.

Validation

• Script compiles and --help runs successfully
• Formatting and lint adjustments were applied on this branch

[Copilot]

Pull request overview

Adds a self-contained, single-file example market maker bot script to demonstrate basic cancel/replace quoting with inventory skew and risk guards using the current Decibel Python SDK APIs.

Changes:

• Introduces examples/write/market_maker_bot.py implementing a periodic quoting loop (fetch state → cancel existing orders → place post-only bid/ask).
• Adds CLI/env configuration for market/network/timing and basic risk limits (inventory and margin usage).
• Implements quote rounding to market tick/lot sizes via SDK utilities.

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[WGB5445]

Addressed all three review points in commit d52a4f4:

1. Dry-run cancel path

• _cancel_market_orders now accepts write: DecibelWriteDex | None.
• _run_cycle now executes cancel handling when (settings.dry_run or write is not None) and open_order_ids, so dry-run can simulate cancel logs.

2. Distinguishable quote outcomes

• Added QuoteStatus and QuoteDecision.
• _compute_quotes now returns explicit statuses (OK, PAUSE_NO_PRICE, PAUSE_INVENTORY_LIMIT, PAUSE_SIZE_INVALID) instead of overloading None.
• _run_cycle branches by status, avoiding misleading inventory-limit messages for size/config issues.

3. Fatal handling for configuration errors

• Main loop now treats ValueError as fatal config errors, prints fatal config error: ..., and exits with non-zero status (2).

Also added focused tests in tests/test_market_maker_bot.py for:

• dry-run cancel simulation without write client
• quote status behavior for size-invalid and inventory-limit cases
• spread-too-tight ValueError
• fatal exit path on config ValueError

Validation run locally:

• ruff check (targeted files)
• ruff format --check
• pytest tests/test_market_maker_bot.py tests/abi/test_registry.py

[Copilot]

Pull request overview

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

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

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[Copilot]

Pull request overview

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

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[Copilot]

Pull request overview

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

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

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[Copilot]

Pull request overview

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

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[Copilot]

Pull request overview

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[gregnazario]

Seems fine, let's add documentation (saying what it does, since it is an example)