fix(sqlite): escape identifiers in PRAGMA queries

[rekurt]

Motivation

• The SQLite loader interpolated table and index names read from database metadata directly into PRAGMA SQL (e.g. PRAGMA table_info("{}")), which can be broken by crafted identifiers containing quotes or semicolons and could lead to parse errors or statement injection.
• A minimal, targeted fix is needed to ensure identifiers are safely quoted before being embedded in PRAGMA statements.

Description

• Replace direct format!(...) interpolation of raw names in PRAGMA table_info, PRAGMA index_list, and PRAGMA index_info with a safe quoting helper and use quote_identifier(...) when building those statements.
• Add a quote_identifier helper that wraps identifiers in double quotes and escapes embedded " by doubling them (SQL-standard identifier quoting).
• Add a unit test test_quote_identifier covering normal identifiers and identifiers with embedded quotes.

Testing

• Added a focused unit test sqlite::tests::test_quote_identifier and attempted to run it with cargo test --lib sqlite::tests::test_quote_identifier.
• Test execution in this environment failed due to network access when fetching crates from crates.io (CONNECT tunnel failed, response 403), so automated tests could not be completed here.

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Codex Task