Add perf / project telemetry

[jakebailey]

This adds events to:

• Project info telemetry, like Strada, with file counts, compiler options (sanitized of course), etc. Sent when we first discover a project, same as Strada.
• Periodically (every 5 mins) send performance info like memory usage, total memory, GC count, allocs, inuse space etc. Plus, the auto import stats. This is new to Corsa.

I added an initialization option that toggles telemetry wholesale; the client is already supposed to ignore it if it doesn't care, but best to not enable it when not needed. Of course, as per usual, telemetry is managed by VS Code and can be controlled like any other extension (and it's all just stats anyway). So the toggle is just for efficiency / testing reasons.

The goal of is is so we can gauge how much we are impacting memory usage. I want to start tweaking GOGC and GOMEMLIMIT but would like to be able to see that it's doing anything.

This introduces a new dep in order to get cross-platform memory info in pure Go.

[Copilot]

Pull request overview

Adds opt-in telemetry emission from the native TypeScript language server to help measure project characteristics and ongoing runtime/performance behavior (memory/GC/auto-import stats), with a new initialization option to enable/disable telemetry.

Changes:

• Introduces enableTelemetry initialization option and plumbs it through LSP server → project session.
• Adds new telemetry event shapes (projectInfo, performanceStats) to lsproto and sends them from internal/project/session.go.
• Adds a cross-platform system memory dependency and updates mocks/tests for the expanded project.Client interface.

Reviewed changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
internal/testutil/projecttestutil/clientmock_generated.go	Updates generated client mock to support SendTelemetry.
internal/project/session.go	Implements periodic performance telemetry and one-time project info telemetry; adds telemetry option and session start time.
internal/project/extendedconfigcache_test.go	Updates test client to satisfy new project.Client interface (SendTelemetry).
internal/project/client.go	Extends project.Client with SendTelemetry.
internal/lsp/server.go	Implements SendTelemetry on the server and wires enableTelemetry init option into session options and panic telemetry gating.
internal/lsp/lsproto/lsp_generated.go	Adds new telemetry event types/unions and enableTelemetry initialization option to generated protocol types.
internal/lsp/lsproto/_generate/generate.mts	Updates generator model with new telemetry events and validates telemetry event measurement/property shapes.
go.mod	Adds github.com/mackerelio/go-osstat for system memory metrics.
_extension/src/client.ts	Enables telemetry in initialization options (currently hard-coded true).