[swjnxyf]

The seven ops subcommands repeated help/error handling, and five parsers independently maintained the same eight common flags. Route these through two private helpers so common connection, credential, and output options have one parsing implementation. Common-option validation now returns Result<(), String> instead of cloning the options.

Command-specific parsing and validation remain local. The change preserves defaults, last-value-wins behavior, flag-like values, first-position help handling, error precedence, exit codes, and credential redaction. Production code decreases by 92 lines; table-driven coverage expands across all seven subcommands.

Validation:

• cargo test --locked -p webcodex-cli --lib tests::ops -- --quiet: 45 tests passed before the change; 46 passed in the final tree, including the existing HTTP/credential and provider-diagnostic tests.
• Before/after comparison of 44,800 generated argv cases: complete parsed actions and help/error outputs were byte-identical. The temporary comparison probe was removed after validation; focused table-driven regressions remain.
• cargo fmt -p webcodex-cli -- --check and git diff --check passed.