feat: list and describe pallet calls/extrinsics in inspect command

Summary

dot inspect currently only shows storage items and constants for a pallet. It should also list and describe pallet calls/extrinsics, which are arguably the most important metadata for users building transactions.

PalletInfo.calls already exists in metadata (src/core/metadata.ts:15) but inspect.ts never displays it — lines 56-98 only show storage + constants, lines 108-142 only search storage + constants.

Motivation

Users need to discover which calls a pallet exposes and what arguments they take before constructing a dot tx command. Currently they must use external tools (Subscan, Polkadot.js Apps) to find this information, defeating the purpose of an integrated CLI.

Proposed Changes

• src/commands/inspect.ts:
  • Add calls count to pallet overview (alongside storage and constants counts)
  • Add "Calls:" section listing all calls with their argument signatures
  • Add call search at item-detail level (e.g. dot inspect Balances.transfer_allow_death)
  • Include calls in the fuzzy suggestion list for typos
• src/commands/inspect.test.ts: Test calls listing and individual call detail

Related Issues

• #54 (tx browsing) — complementary, not duplicative. #54 is about interactive browsing in dot tx; this is about inspect.
• #74 (storage details in inspect) — same file, different sections.

Priority

P1 — Unblocks discoverability for everything else. Quick win (size S).

Start with src/commands/inspect.ts, especially the overview and search sections at lines 56-98 and 108-142, and review PalletInfo.calls in src/core/metadata.ts. Add call counts, argument signatures, detail lookup, and fuzzy suggestions, then run the related tests in src/commands/inspect.test.ts to verify listing and individual call details.