Keeper: Logging Improvements for Loki

[aoikurokawa]

No description provided.

[Copilot]

Pull request overview

This PR standardizes and restructures logging across the keeper/writer services to be more Loki-friendly (key=value style) and to improve error formatting consistency.

Changes:

• Replaces verbose/pretty debug logs with structured key=value messages (e.g., epoch=..., count=...).
• Standardizes error logging to prefer {e:#} formatting for more informative error output.
• Adjusts log levels/messages in a few flows (e.g., retry warnings, clearer service-specific wording).

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
writer-service/src/stake_pool_manager.rs	Tweaks stake pool stats log output to be less verbose/structured.
writer-service/src/main.rs	Standardizes live/backfill error logging formatting.
writer-service/src/lib.rs	Standardizes error logs around DB write operations for multiple writers.
writer-service/src/bam_boost_manager.rs	Adds structured context (url/epoch) to BAM boost merkle tree fetch/parse logs.
steward-writer-service/src/main.rs	Converts multiple logs to structured fields; improves retry/error severity and messages.
cranker/src/utils.rs	Refactors transaction/update logging strings toward structured output.
cranker/src/main.rs	Standardizes error/warn formatting for update + Slack + polling retries.
bam-writer-service/src/main.rs	Makes epoch-threshold progress logs structured and more service-specific.
bam-writer-service/src/lib.rs	Makes override/skip logs more structured and consistent with key=value style.

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