[FEATURE] Allow customizing the past tense thinking verb ("Cogitated for X")

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

After Claude finishes thinking, it shows a line like:

✻ Cogitated for 1m 18s

The spinnerVerbs setting in settings.json already lets you customize the verbs shown during processing (e.g., "Grumbling...", "Analyzing..."), but the past tense completion verb ("Cogitated") doesn't appear to be configurable.

This matters for anyone building personality/theme systems on top of Claude Code. For example, we maintain claude-personalities — a community plugin that lets users swap Claude's tone, statusline, and spinner verbs to match characters like Marvin, JARVIS, Chopper, etc. We can customize everything except this one verb, which breaks the immersion.

Proposed Solution

Add a pastTenseVerbs (or completionVerbs) setting alongside the existing spinnerVerbs in settings.json:

{
  "spinnerVerbs": {
    "mode": "replace",
    "verbs": ["Grumbling", "Warbling", "Zapping"]
  },
  "pastTenseVerbs": {
    "mode": "replace",
    "verbs": ["Grumbled", "Warbled", "Zapped"]
  }
}

Claude would randomly pick from the list when displaying the completion line, just like it does with spinner verbs.

Alternative Solutions

• Derive past tense automatically from spinnerVerbs — e.g., "Analyzing" → "Analyzed". This would be simpler but less flexible (some verbs have irregular past tenses).
• Add a pastTense field to each spinner verb — e.g., {"present": "Grumbling", "past": "Grumbled"}. More structured but more verbose.
• Currently there's no workaround — the past tense verb can't be changed.

Priority

Medium - Would be very helpful

Feature Category

Configuration and settings

Use Case Example

1. User installs the claude-personalities plugin
2. Runs /claude-personalities:swap and picks "Marvin the Paranoid Android"
3. Spinner verbs change to "Sighing...", "Despairing...", "Brooding..." ✅
4. Statusline updates with Marvin's quips ✅
5. But after thinking completes: "Cogitated for 1m 18s" — breaks character ❌
6. With this feature: "Despaired for 1m 18s" — perfect ✅

Additional Context

The spinnerVerbs setting was a great addition — this would be the natural companion to complete the customization story. The community plugin already has 17 personalities and growing, each with unique spinner verbs that would benefit from matching past tense verbs.