fix(code-intelligence): prepare cold workspace symbol queries

[ZhiXiao-Lin]

Summary

• synchronize a saved source document before each active language runtime handles its first workspace-symbol search
• add a process-level regression fixture that rejects workspace-symbol requests until document open
• prepare the 5.3.4 patch release and advance the SemVer baseline to 5.3.3

Verification

• cargo fmt --all -- --check
• cargo clippy --workspace --lib --bins -- -D warnings
• cargo test --workspace
• cargo test --workspace --all-features --lib
• cargo check --manifest-path sdk/node/Cargo.toml
• cargo check --manifest-path sdk/python/Cargo.toml
• bash scripts/check_semver.sh 5.3.3
• real TypeScript language server cold workspace-symbol query