📝 Document pi-lsp tooling and agent usage

README § Tooling and § Tooling decisions record the extension and the
reasoning behind it: read-only by design, auto-detects TypeScript 7,
and never a correctness gate — verify is. AGENTS.md § First action tells
agents the lsp_* tools exist, to prefer lsp_references over grep -w for
colliding identifiers, and to treat empty LSP output as inconclusive.

Close the backlog evaluation task with a resolved note, and allowlist
the tsgo/tsserver tool names for cspell.

cspell.json

@@ -19,6 +19,8 @@
         "arethetypeswrong",
         "knip",
         "tsgolint",
+        "tsgo",
+        "tsserver",
         "gitea",
         "pubv",
         "knope",