Move duplicated quoting DB logic for OB and autopilot into shared

[AryanGodara]

Description

The QuoteStoring save/get/find impls were duplicated for orderbook and autopilot. Moves them into shared/quote_storage.rs, where the fast-path save_quote_competition logic already live, so both flows share singular implementation.

Changes

• Add save_quote, get_quote, find_quote to shared::quote_storage, each taking &PgPool and owning its own connection/transaction.
• Make save_quote_competition private. its only caller is now save_quote.
• Both QuoteStoring for Postgres impls just start a metrics timer and delegate; the timer stays per-crate (separate Metrics types).
• Add a database::PgPool type alias so shared names the pool type without a direct sqlx dependency.

How to test

Existing unit and e2e tests (no expected behaviour chagnes)

Closes BE-284

[linear-code]

BE-284

[claude]

Claude finished @AryanGodara's task in 1m 13s —— View job

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PR Review: Move duplicated quoting DB logic into shared

Reviewed the refactor. This is a clean, behavior-preserving move — no blocking issues found. ✅

What I verified:

• The save/get/find QuoteStoring impls were byte-for-byte identical between orderbook and autopilot on origin/main, so consolidating them into shared::quote_storage is safe. The moved bodies (transaction handling, connection acquisition, create_db_search_parameters, error context) match the originals exactly.
• Both call sites correctly keep their per-crate metrics timer and just delegate — the separate Metrics types stay intact.
• save_quote_competition is now private with save_quote as its only caller; no other references remain (the persistence/mod.rs:1216 hit is just a doc comment).
• Removed imports (create_db_search_parameters) are genuinely unused now, and Context is still used in both files, so no dangling/unused imports.
• The database::PgPool alias is a reasonable way to let shared name the pool type at the crate boundary.

Minor (non-blocking) nit: the module doc at crates/shared/src/quote_storage.rs:1-3 is now slightly stale — it describes the helpers as shared between the QuoteStoring::save implementations, but the module now also owns get_quote/find_quote, which aren't specific to quote competitions. Consider broadening the wording, e.g.:

Persistence helpers for quotes and quote competitions. Shared between the orderbook and autopilot QuoteStoring implementations…

(Couldn't attach this inline since those lines aren't part of the diff.)
· Branch: aryan/be-284-moveduplicated-quoting-logic-to-shared