What does this PR do?

• On tools/call, split the bare except Exception so that a TypeError matching Python's signature-mismatch shape returns a structured -32602 Invalid params naming the offending parameter(s), instead of the opaque -32000 Internal tool error. Multi-arg cases list each name.
• Match is gated on the function name in the TypeError equalling the dispatched handler's __qualname__, so a downstream helper that happens to raise a similar-looking TypeError falls through to the generic path. Handler-internal TypeError and all non-TypeError exceptions stay on the existing generic -32000 path with no exception strings reaching the client.
• tool_args.pop("wait_for_previous", None) is moved one line above the try: so the new except TypeError branch only sees exceptions from the dispatched handler call.
• Adds TestParamShapeDiagnostics in tests/test_mcp_server.py with 6 cases: single missing-required, two missing-required listing both names, handler-internal TypeError with unrelated message stays generic, handler-internal TypeError with signature-mismatch shape stays generic, handler-raised got an unexpected keyword argument shape stays generic, and RuntimeError stays generic with no path leak.

How to test

uv run pytest tests/test_mcp_server.py -v -k ParamShape
uv run pytest tests/ -q --ignore=tests/benchmarks
uv run ruff check . && uv run ruff format --check .

End-to-end repro from #1351:

echo '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"mempalace_diary_write","arguments":{"agent_name":"test"}}}' \
  | uv run python -m mempalace.mcp_server

Before this PR returns -32000 "Internal tool error". After: -32602 "Missing required parameter 'entry' for tool mempalace_diary_write". With both args omitted: -32602 "Missing required parameters 'agent_name', 'entry' for tool mempalace_diary_write".

Checklist

• Tests pass (python -m pytest tests/ -v)
• No hardcoded paths
• Linter passes (ruff check .)

Why

Addresses the missing-required half of #1351. The reporter surfaces a missing-required call as -32000 Internal tool error, which hides which parameter is wrong; agents (LLM and otherwise) end up retrying the same wrong-shape call multiple times before checking the schema. The wrong-name case (e.g. text= vs content=) is silently absorbed by the schema-filter at mempalace/mcp_server.py:2235 before dispatch and is being tracked as a follow-up by @anastasiiaanfimova.

-32602 matches the JSON-RPC 2.0 spec for invalid params and the existing precedent in this file (line 2207 for missing name on tools/call, line 2251 for the type-coercion failure path). Only parameter names that are already public via tools/list reach the client; handler-internal TypeError and any non-TypeError exception still resolve to generic -32000, so ChromaDB or filesystem internals never leak.

Complementary to the error-hardening direction in #181: the catch-all path stays generic, only param-shape errors become structured.

@anastasiiaanfimova's comment on #1351 outlined the dispatcher-TypeError reformatting approach this PR builds on; she's added as Co-authored-by on the commit.