refactor: add QueryContext and simplify LinkedQuery

[zharinov]

Summary

• Add QueryContext<'a> struct that bundles the commonly-passed analysis context (interner, type_ctx, symbol_table)
• Add context() accessor to QueryAnalyzed for downstream modules
• Refactor LinkedQuery to reuse LinkOutput instead of duplicating its fields

Motivation

Analysis of the compiler pipeline revealed that QueryAnalyzed already bundles the core context but doesn't expose it coherently. Downstream modules (compile, emit) extract these individually:

// Before: 6 separate extractions
Compiler::compile(
    query.interner(),
    query.type_context(),
    &query.symbol_table,
    ...
)

// After: unified context available
let ctx = query.context();

Additionally, LinkedQuery was duplicating LinkOutput fields instead of reusing the struct.

Test plan

• All 677 lib tests pass
• All 14 CLI tests pass