chore: remove dead Copilot inspection code

[chagong]

What

Removes the entire src/copilot/ directory — the Copilot-powered Java "inspection" feature (LLM-generated suggestions rendered as code lenses, gutter icons, ruler highlights, and diagnostics).

Why

The feature's activation entry was removed from extension.ts in #1343 (shipped in v0.27.0), but the implementation itself was left in the tree as unreferenced dead code. On the current main:

• Nothing outside src/copilot/ imports any of these modules.
• activateCopilotInspection is defined but never called.
• There are no package.json command/menu/configuration contributions pointing at it (those were removed in remove entry of Copilot related features. #1343).
• The java.copilot.* commands are only registered programmatically inside the never-invoked activation path.

So the code can never run today. Removing it reduces bundle size and eliminates confusion.

Scope / safety

• Deletes only src/copilot/** (15 files).
• No dependency changes needed: lodash and vscode-extension-telemetry-wrapper remain used elsewhere in the extension.
• No package.json contribution changes needed (none referenced this feature).

Validation

• npx tsc --noEmit — passes.
• npm run compile (webpack) — builds successfully.

[Copilot]

Pull request overview

Removes the previously deactivated Copilot-powered Java “inspection” feature implementation by deleting the entire src/copilot/** subtree, reducing bundle size and eliminating dead/unreachable code paths.

Changes:

• Delete the Copilot inspection core (chat wrapper + inspection orchestration and caching).
• Delete all inspection UI renderers (CodeLens, diagnostics, gutter icons, ruler highlights) and command wiring.
• Delete related symbol utilities used only by the removed feature.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/copilot/utils.ts	Removes Copilot inspection utilities (symbol/range helpers, telemetry wrappers, LM API readiness checks).
src/copilot/Copilot.ts	Removes the Copilot chat wrapper used by the inspection feature.
src/copilot/inspect/SymbolNode.ts	Removes the DocumentSymbol wrapper used for inspection targeting/caching.
src/copilot/inspect/Inspection.ts	Removes the inspection data model and indicator-range helper.
src/copilot/inspect/InspectionCache.ts	Removes inspection caching keyed by document/symbol snapshots.
src/copilot/inspect/InspectionCopilot.ts	Removes the inspection engine that prompts the model and parses suggestions.
src/copilot/inspect/commands.ts	Removes command registrations for inspect/fix/ignore flows.
src/copilot/inspect/index.ts	Removes the (now-dead) activation entrypoint and dependent-extension waiting logic.
src/copilot/inspect/DocumentRenderer.ts	Removes renderer management and rerender/debounce logic for inspection UI.
src/copilot/inspect/InspectActionCodeLensProvider.ts	Removes the “Rewrite with new Java syntax” class-level CodeLens provider.
src/copilot/inspect/render/InspectionRenderer.ts	Removes the shared renderer interface used by inspection UI implementations.
src/copilot/inspect/render/CodeLensRenderer.ts	Removes inspection CodeLens rendering implementation.
src/copilot/inspect/render/DiagnosticRenderer.ts	Removes diagnostic publishing + code action generation for fixes.
src/copilot/inspect/render/GutterIconRenderer.ts	Removes gutter icon decoration rendering and fix-command hover wiring.
src/copilot/inspect/render/RulerHighlightRenderer.ts	Removes overview ruler highlight decoration rendering.

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