[M10] Implement diagnostics, hover, definition, and reference language services

[Teakowa]

Parent: #27

Depends on: #63, #64

Planning status: provisional until the M9 gate is complete.

Goal

Expose the first high-value editor-neutral language intelligence by composing the native frontend, semantic index, analyzer, and project/workspace model.

Scope

• Publish syntax/semantic/static-analysis diagnostics for the current document/project state.
• Implement hover information backed by canonical symbols, target catalog metadata, and source semantics.
• Implement go-to-definition for supported declarations/references across files.
• Implement find-references using the existing semantic index/project graph.
• Preserve precise source ranges and document versions in all results.
• Handle incomplete/malformed source conservatively using parser recovery without inventing semantic certainty.

Non-goals

• LSP wire serialization.
• Heuristic symbol guesses that are not supported by the semantic model.
• Completion/rename/semantic tokens; separate issue.

Acceptance criteria

• Core diagnostics/navigation operations work through editor-neutral APIs.
• Cross-file definition/reference results match compiler project/source resolution.
• Results update correctly after document changes and do not return stale document versions.
• Incomplete source degrades gracefully with structured partial/unavailable results rather than panics.

[Teakowa]

Delivered in commit 7b0d0f2.

• diagnostics: structured parse errors and analyzer findings with ranges/severity/code/version (tested incl. malformed input and min-wait-loop).
• hover: symbol name/kind + usage summary (reads/writes/calls/rules).
• definition: declaration range via the semantic index; references: all reference ranges across the project model.
• All composed from the native frontend + M4 semantic index + analyzer (tests in crates/wright-language/tests/service.rs).

[Teakowa]

Remediated and re-verified (commits 5935310, c8c17b2).

• Diagnostics/hover unchanged; definition prefers the symbol's definition site and returns SourceLocation; references returns Vec<SourceLocation>.
• Navigation is source/file-aware: span.file maps to the main document URI or a resolved included-file path, and the LSP adapter maps each location to the correct target URI.
• Real multi-file fixtures (crates/wright-language/tests/fixtures/multifile/) prove cross-file definition/references at both the language-service and LSP harness boundaries.