Revise SECURITY.md for version support and reporting

add _stmt_cache_size to DSN parameters table in README

Merge pull request #1387 from mattn/codex/stmt-cache

document that _stmt_cache_size is per connection

move reset/clear into putCachedStmt and always finalize on failure

simplify prepareWithCache to call prepare instead of duplicating logic

do not bail out on finalize error in closeCachedStmtsLocked

remove redundant stmtCacheSize check in putCachedStmt

check stmtCacheSize before acquiring mutex in takeCachedStmt

add opt-in statement cache

Merge pull request #1386 from mattn/perf/reduce-cgo-overhead

fix build with SQLITE_ENABLE_UNLOCK_NOTIFY

reduce CGO call overhead for exec and bind paths

Merge pull request #1385 from mattn/perf/reduce-bind-overhead

reduce sqlite bind overhead