statusline-install

**Project scope:**
1. Write the script to `.claude/statusline-command.sh` in the current project root
2. Make it executable: `chmod +x .claude/statusline-command.sh`
3. Read the project's `.claude/settings.json` (create if needed)
4. Set the `statusLine` field to:
   ```json
   {
     "type": "command",
     "command": "bash .claude/statusline-command.sh"
   }
   ```
5. Write back the updated settings (preserve all other fields)

**Global scope:**
1. Write the script to `~/.claude/statusline-command.sh`
2. Make it executable: `chmod +x ~/.claude/statusline-command.sh`
3. Read `~/.claude/settings.json`
4. Set the `statusLine` field to:
   ```json
   {
     "type": "command",
     "command": "bash ~/.claude/statusline-command.sh"
   }
   ```
5. Write back the updated settings (preserve all other fields)

**4a. Probe for a patched font (fast, no dependencies).**

Do NOT use `fc-list` — fontconfig is usually absent on macOS. Scan the font
directories by filename instead:

```bash
find ~/Library/Fonts /Library/Fonts /System/Library/Fonts \
  -maxdepth 2 \( -type f -o -type l \) 2>/dev/null \
  | grep -Ei 'nerd|NF-|powerline' | head -5
```

**4b. No matches → do not ask.** Write `icons.nerd_font: false` (see 4d) and
move on. Mention it in the report as one line, nothing more.

**4c. Matches found → ask, showing the real glyph.** A font inventory is NOT
enough to decide: Nerd Font coverage is **partial and varies by font**. On a
machine with 0xProto Nerd Font installed, `U+F035B` (nf-md-memory) renders
correctly while `U+F2DB` (nf-fa-microchip) and `U+F4BC` (nf-oct-cpu) come out
as blank space. Only the user can confirm the specific glyph resolves.

Print the sample line first — it must contain the actual glyph the plugin
will use, in context:

```
Found a Nerd Font: <first matching filename>

With icons:     󰍛 1.1G
Without icons:  RAM 1.1G
```

Then use AskUserQuestion:
- question: "In the line above, do you see a RAM-stick icon before `1.1G`?"
- options:
  1. "Yes, I see an icon" — enables Nerd Font glyphs (`icons.nerd_font: true`)
  2. "No — a box, or blank space" — keeps text labels (`icons.nerd_font: false`)

"Blank space" is an explicit option on purpose: a missing glyph often renders
as nothing rather than as tofu, and a user skimming for a box will answer yes
to an empty gap.

**4d. Write the answer, merging — never clobbering.**

The config file is `~/.claude/statusline-config.json` for **both** scopes: the
script always reads it from `$HOME`, even when installed project-scoped.

1. Read `~/.claude/statusline-config.json` (may not exist — then start from `{}`)
2. Set only `icons.nerd_font` to the boolean answer, leaving every other key
   untouched (users commonly have `sections`, `theme`, `context_bar_width`)
3. Write the merged object back