fix(dart): handle analyzer status notifications

[jiatianzhao]

Problem

The Dart analysis server emits $/analyzerStatus notifications while it analyzes a workspace. Serena's Dart adapter did not register this server-specific notification, so the generic notification dispatcher logged every event as an unhandled-method warning. This creates repeated warning noise even though the notification does not require action from Serena.

Cause

The Dart adapter already registers no-op handlers for other informational notifications such as $/progress and language/status, but $/analyzerStatus was missing from that adapter-specific list. The global dispatcher therefore treated it as genuinely unknown.

Fix

Register $/analyzerStatus with the Dart adapter's existing no-op handler. Global handling of unknown notifications is unchanged, so unexpected methods from other servers continue to produce warnings.

Add a regression test that starts the Dart adapter against an in-memory LSP interface, sends $/analyzerStatus through the production notification dispatcher, and verifies that the unhandled-method warning is not emitted.

Verification

• Regression test fails on main with Unhandled method '$/analyzerStatus' and passes with this change.
• uv run poe test -m dart -q --tb=short: 22 passed, 2 skipped.
• uv run poe lint: passed.
• uv run poe type-check: passed.
• uvx --from codespell codespell CHANGELOG.md src/solidlsp/language_servers/dart_language_server.py test/solidlsp/dart/test_dart_startup.py: passed.

Compatibility

No public API, configuration, dependency, or global notification behavior changes.

Fixes #1855

Disclosure

Prepared with assistance from OpenAI Codex. I reviewed the implementation and test design and ran the verification above.

Checklist

• This PR follows the guidelines in CONTRIBUTING.md regarding the scope of PRs.
• For changes that add features or fix problems, I have added an entry to CHANGELOG.md, which concisely describes the change.

[opcode81]

Precondition for merging: Test this with an actual project using the Dart language server, verifying that

• the state prior to the change produces the undesirable log message
• the new state does not.

[jiatianzhao]

I verified this with the real Dart language server using Serena's pinned Dart SDK 3.7.1 on macOS arm64.

I ran the same four-file Dart project with:

serena project index <project> --ls dart --log-level WARNING --timeout 30

At the base commit (7067f566), indexing completed successfully and emitted 18 warnings, including:

WARNING ... solidlsp.ls_process:_notification_handler:474 - Unhandled method '$/analyzerStatus'
Indexed files per language: dart=4

At the PR head (8042aaeb), indexing completed successfully with the same result and no $/analyzerStatus warnings:

Indexed files per language: dart=4

[opcode81]

Thanks for your contribution!