release: integrate Code features for v5.3.6

[ZhiXiao-Lin]

Summary

• integrate the TypeScript profile, PDF fetch, session fork, typed MCP, and conversational-turn changes from feat(code-intelligence): expand TypeScript language profiles #11 through fix(agent): keep standalone greetings tool-free #15
• preserve every Unreleased changelog entry while resolving the shared changelog conflicts
• prepare Core, Node, Python, and bootstrap versions for 5.3.6
• advance the SemVer baseline to the verified 5.3.5 crate

Validation

• cargo fmt --all -- --check
• cargo clippy --workspace --lib --bins -- -D warnings
• cargo test --workspace (2453 passed)
• cargo test --workspace --all-features --lib (2499 passed)
• event protocol and SDK API alignment checks
• release version and locked metadata checks

Closes #11
Closes #12
Closes #13
Closes #14
Closes #15