docs: add simulation failures and settlement guide for priority orders (PROTO-1329)

[pinky-gh]

What

Adds a new guide at docs/contracts/uniswapx/fillers/priority/simulation-and-settlement.md covering:

• Why block-timing reverts are expected for UniswapX priority orders (and should not be treated as fatal errors)
• A decision tree for retry vs. skip logic when simulations fail
• An error code reference table for common revert reasons
• A Base L1 data fee warning for fillers operating on Base

Also updates filleroverview.md with a cross-link to the new guide.

Why

Closes/relates to PROTO-1329.

Priority order fillers have been encountering confusing simulation failures due to block-timing sensitivity. This guide gives fillers the context they need to distinguish expected reverts from genuine errors, and prescribes the correct retry/skip behavior to avoid missed fills and unnecessary gas spend.

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Project	Deployment	Actions	Updated (UTC)
docs	Ready	Preview, Comment	May 6, 2026 9:21pm