docs(inkless): fix performance docs

[jeqo]

Fix links from FAQ, and adds more detail on how consumer-side and caching performance implications work.

[Copilot]

Pull request overview

This pull request improves the Inkless performance documentation by fixing a broken link in the FAQ and adding comprehensive content about consumer-side caching and performance optimization. The changes provide detailed explanations of how Inkless's caching architecture works with AZ-aware partition assignment, the hot/cold path separation for handling recent vs. lagging consumer requests, and practical tuning guidance.

Changes:

• Fixed markdown link syntax in FAQ.md for the performance tuning guide reference
• Added detailed sections on consumer caching architecture, AZ-awareness, and cache efficiency
• Documented hot/cold path separation for managing recent data vs. lagging consumer requests
• Provided comprehensive tuning guidance for both broker and consumer configurations
• Added monitoring metrics documentation and performance optimization recommendations

Reviewed changes

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

File	Description
docs/inkless/FAQ.md	Fixed broken link to PERFORMANCE.md by correcting markdown syntax from parentheses to square brackets
docs/inkless/PERFORMANCE.md	Added extensive documentation (169 lines) covering consumer performance, caching behavior, AZ-awareness, hot/cold path architecture, tuning configurations, monitoring metrics, and performance optimization strategies

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[giuseppelillo]

In this specific case cross-AZ data transfer are effectively 0

[jeqo]

Good catch. Will clarify this in a fixup commit. PTAL

[giuseppelillo]

LGTM with a comment.
Will add some docs about the batch coordinate cache in another pr.