feat(mcp): --with-output-style auto-activates the style (no manual /style needed)

[aomerk]

Summary

keeba mcp install --with-output-style now also flips outputStyle: \"keeba\" in ~/.claude/settings.json so the style is active on the next Claude Code launch without the user typing any slash command. Closes the UX cliff where the install dropped the file on disk but the style was never actually used.

Why

Real user report from a v2.1.126 session:

❯ /output-style keeba
Unknown command: /output-style

❯ /style keeba
Unknown command: /style

Claude Code v2.x removed (or renamed) the per-session output-style slash command. The settings.json outputStyle key is the only stable activation surface across versions — confirmed by inspecting the binary (outputStyle:OH?.outputStyle in localSettings save path).

Until this PR, --with-output-style left users with a file on disk and no way to activate it. The terse style we shipped in PR #35 + the inter-tool-silence rule in PR #38 did nothing for them.

How

Adds activateKeebaOutputStyle(settingsPath string) (bool, error):

• Reads existing ~/.claude/settings.json (or starts empty if missing)
• Sets outputStyle: \"keeba\", preserving every other key
• Writes back as indented JSON
• Idempotent: returns (false, nil) if already set to "keeba"

Wired into applyClaudeCodePatches after installKeebaOutputStyle so re-running install prints "no change" cleanly when both halves are already done.

Test plan

• go test ./internal/cli/... — green (4 new tests: fresh-file, preserves-existing-keys-including-hooks, idempotent, overwrites-different-style)
• gofumpt -l clean, golangci-lint run 0 issues
• End-to-end with synthetic HOME:
  • Pre-existing settings.json with theme + effortLevel
  • keeba mcp install --tool claude-code --with-output-style runs
  • Result: {theme, effortLevel, outputStyle: \"keeba\"} — all three preserved
  • Re-run prints "no change" for all install steps

What this means for users

After merge + reinstall:

keeba mcp install --tool claude-code \\
  --patch-agents --with-claude-md --with-hook --with-output-style
# restart Claude Code → terse style is active automatically

No /output-style or /style activation needed. The install is the install.

🤖 Generated with Claude Code