Add opt-in lazy language-server initialization

[TyceHerrman]

Problem

Codex may create multiple stdio MCP runtimes for one project. With Serena 1.6.1, four Serena processes started four rust-analyzer instances within 23 seconds; three reached 9.25–9.76 GB before the machine crashed.

Codex owns runtime reuse and cleanup, as discussed in #693 and openai/codex#30408. This request is for an optional Serena-side guard.

PR #227 made language-server initialization asynchronous but still starts it during project activation. True first-use initialization was previously prototyped but not merged:

• fix: make project initialization asynchronous to prevent MCP timeout (fixes #201) #209 (comment)
• dayowe@9816058

Requested solution

Add an opt-in lazy mode:

• Do not start language servers during project activation.
• Initialize once through the existing serialized queue when the first dependent tool runs.
• Let non-LSP tools run without triggering initialization.
• Handle concurrent first calls, failures, restarts, project switching, and shutdown.
• Keep eager initialization as the default.

The tradeoff is latency on the first dependent call.

[opcode81]

This probably won't be necessary if #1556 is addressed, so I would prioritise that.
PR #1557 already exists, but isn't finished.

[TyceHerrman]

Great! missed that in reviewing prior work. I'll check it out

[opcode81]

Closing as "not planned" for now.