Phases 01+02 of #1162. Splits executor flag parsing/validation out of the
1428-LOC orchestrator into a focused module:
New files:
- src/cliproxy/executor/arg-parser.ts (~500 LOC):
readOptionValue, hasGitLabTokenLoginFlag, getGitLabTokenLoginFlagName,
CCS_FLAGS + filterCcsFlags, ParsedExecutorFlags + parseExecutorFlags,
validateFlagCombinations (process.exit semantics preserved for parity).
- src/cliproxy/executor/__tests__/arg-parser.test.ts: 45 unit tests.
- src/cliproxy/executor/__tests__/index-characterization.test.ts:
TDD baseline (16 pass + 7 skipped scenarios at the spawn/dynamic-import
boundary; mock simplification deferred to a follow-up phase).
index.ts: 1428 -> 1175 LOC (-253). Re-exports preserved at module bottom
for backwards compatibility. Behavior unchanged; full test suite passes
(1824/1824).
Refs #1162
