Add an inline inlay-hint display mode

[Ky6uk]

Summary

Add an optional inline display mode based on VS Code inlay hints while preserving CodeLens as the initial default.

Motivation

The current CodeLens provider analyzes every eligible symbol in a document and adds a dedicated row above each result. An inlay hint provider receives a requested document range, so inline mode can limit reference lookups to symbols in that range and avoid vertical layout changes.

Scope

• Add zeroReference.displayMode with codeLens and inline values.
• Register an InlayHintsProvider for the existing TypeScript and JavaScript document selectors.
• Reuse the existing symbol eligibility, declaration grouping, concurrency, cancellation, and stale-result rules.
• Analyze only eligible declarations contained by the requested range.
• Render a compact 0 workspace references hint at the declaration line.
• Ensure only the selected display provider is active.
• Share refresh and invalidation behavior with CodeLens mode.

Acceptance criteria

• Inline mode emits hints only for declaration-only reference groups.
• No reference lookup is made for a declaration outside the requested range.
• Changing the display mode refreshes the editor without reloading the extension host.
• Cancellation, document changes, and configuration changes discard stale results.
• A focused regression test proves that a large document performs lookups only for symbols in the requested range.
• Existing CodeLens behavior remains the default for the first release.

Dependencies

• Keep analysis results fresh across files and cache unchanged documents #17 for shared cache invalidation and refresh behavior.

Out of scope

• Making inline mode the default without real-world UX and performance validation.
• Adding new language identifiers.