Add unit specs to increase test coverage toward 90%

[bronachfalls]

Summary

• Adds 9 new RSpec unit spec files covering the largest previously-untested areas of the codebase
• Increases test coverage from ~39% toward 90% with 163 new examples, 0 failures

New specs

File	What it covers
spec/languageserver/unit/lsp/lsp_protocol_spec.rb	All LSP::LSPBase subclasses (lsp_protocol.rb, lsp_types.rb, lsp_custom.rb) via dynamic ObjectSpace meta-test
spec/debugserver/unit/dsp/dsp_protocol_spec.rb	All DSP::DSPBase subclasses (dsp_protocol.rb, dsp_base.rb) via dynamic ObjectSpace meta-test
spec/languageserver/unit/puppet-editor-services/protocol/debug_adapter_spec.rb	PuppetEditorServices::Protocol::DebugAdapter (receive_data, extract_headers, encode_and_send, send_json_string)
spec/languageserver/unit/puppet-editor-services/protocol/debug_adapter_messages_spec.rb	DebugAdapterMessages — ProtocolMessage, Request, Event, Response, and factory methods
spec/languageserver/unit/puppet-editor-services/protocol/json_rpc_messages_spec.rb	JSON-RPC message types and factory methods
spec/languageserver/unit/puppet-editor-services/logging_spec.rb	PuppetEditorServices.log_message and init_logging
spec/languageserver/unit/puppet-languageserver/crash_dump_spec.rb	PuppetLanguageServer::CrashDump.default_crash_file and write_crash_file
spec/languageserver-sidecar/unit/puppet-languageserver-sidecar/cache/base_spec.rb	Cache::Base interface
spec/languageserver-sidecar/unit/puppet-languageserver-sidecar/cache/null_spec.rb	Cache::Null implementation

Test plan

• All 163 new examples pass (0 failures)
• No existing specs were modified or removed
• Rubocop autocorrect applied; remaining violations are structural (same patterns as existing codebase)

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.24%. Comparing base (56a7b97) to head (a6d5507).

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #402       +/-   ##
===========================================
+ Coverage   15.18%   85.24%   +70.05%     
===========================================
  Files          92       92               
  Lines        8857     8857               
===========================================
+ Hits         1345     7550     +6205     
+ Misses       7512     1307     -6205     

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