[v1.11] Short-flag namespace audit (rip and replace)

[seabearDEV]

Problem

Short-flag space is inconsistent across commands. Symptom: --plain shipped without a short flag in v1.9.1 because -p was already taken by --preview elsewhere, and -P felt awkward as a one-off. The codex entry context.shortFlagAudit flags this as pending tech debt with a clear directive: "Don't add new short flags piecemeal — wait for the audit so the whole namespace gets reorganized at once."

Goal

Single coherent reassignment of every short flag across every command and subcommand. Rip-and-replace, no deprecation cycle.

Proposed approach

1. Inventory every existing short flag across all commands and subcommands
2. Identify collisions, near-collisions, and orphans (--plain and any others without shorts)
3. Propose a coherent assignment that minimizes user-visible churn while resolving conflicts
4. Land in one PR with a single CHANGELOG entry listing every flag that moved

Acceptance criteria

• Full short-flag inventory (commands, subcommands, current assignments)
• Coherent reassignment proposal with rationale
• All collisions resolved
• --plain and any other orphans get short flags
• CHANGELOG.md lists every flag move under [Unreleased] → Changed
• Help text and zsh completions regenerated