Refactor tx.ts: split into tx-parse, tx-submit, tx-display modules

Problem

tx.ts is ~850 lines and handles parsing, submission, and display — three distinct concerns in one file. This makes it harder to navigate, test, and reuse individual pieces (e.g., parseTypedArg is needed by query.ts too).

Proposal

Split into focused modules:

Benefits

• parseTypedArg becomes importable by query.ts (see type-aware query keys issue)
• Each module is independently testable
• Easier to navigate and review
• Clear separation of concerns

Acceptance Criteria

• tx.ts reduced to command registration and orchestration (~100-150 lines)
• Parsing, submission, and display logic extracted to separate files
• No behavior changes — all existing tests pass
• parseTypedArg is importable from tx-parse.ts for reuse

Start by reading tx.ts to map the parsing, submission, display, and CAC orchestration responsibilities, then check query.ts for the planned parseTypedArg reuse. Extract the listed exports into tx-parse.ts, tx-submit.ts, and tx-display.ts while keeping tx.ts focused on registration and wiring. Done means tx.ts is about 100–150 lines, parseTypedArg is importable, and all existing tests pass without behavior changes.