Make CodeLens compact, actionable, and scope-aware

[Perdolique]

Summary

Make Zero Reference findings compact, actionable, honest about their scope, and explicit about configuration target.

Motivation

The current CodeLens repeats the symbol name in a full sentence and uses an empty command. The Toggle CodeLens command can also update the global setting when no workspace override exists, without telling the user which scope changed.

Scope

• Replace "<symbol>" has zero references with 0 workspace references.
• Add a tooltip explaining that external and dynamic consumers might not be visible to the current language server.
• Give CodeLens and inline labels a real command.
• Present relevant actions such as refresh, ignore this declaration, and open Zero Reference settings.
• Replace the opaque toggle with explicit workspace and global enable/disable commands, or an equally clear scope selection.
• If display modes are introduced, migrate from the implementation-specific useCodeLens setting to an enabled setting without breaking existing configuration.
• Avoid informational notification spam during normal editing.

Acceptance criteria

• Every rendered CodeLens has a meaningful command and tooltip.
• The label does not repeat the declaration name.
• Workspace commands never mutate global configuration, and global commands never create a workspace override.
• Existing zeroReference.useCodeLens values are migrated or honored with a documented deprecation path.
• Command visibility and configuration-target behavior have Extension Host tests.

Dependencies

• Add exclusions and per-symbol suppression #18 for the Ignore this symbol action.
• Add an inline inlay-hint display mode #1 when sharing actions with inline display mode.