feat(cli): Add `--quiet` flag to suppress non-essential output

[sunilp]

Summary

Add a global --quiet / -q flag that suppresses all non-essential output (spinners, status messages, decorative elements), leaving only the AI response or command result.

Use Case

Important for scripting and piping:

jam ask "What is 2+2?" --quiet    # just the answer, no spinners or decorations
jam search "TODO" --quiet          # just the search results

Implementation Notes

• Add --quiet to the global options in src/index.ts
• Pass through to commands via globalOpts()
• Suppress: logo, spinners, status lines, decorative separators
• Keep: the actual AI response, search results, error messages

Acceptance Criteria

• --quiet / -q flag available on all commands
• Only essential output when flag is set
• Works correctly with --json (already minimal, but should suppress any extra output)
• Documented in README options table

[sunilp]

✅ Implemented and verified — closing

Merged in #11 (commit 1c908d9).

Delivered:

• -q, --quiet global option added to src/index.ts
• Passed through globalOpts() to runAsk() via the AskOptions interface
• In src/commands/ask.ts: a stderrLog function is set to a no-op when --quiet is active, silencing all status lines, separators, tool call logs, and token usage output
• The AI response itself (stdout) is always printed regardless of the flag

Test results — 160/160 pass, 0 regressions (npm test):

✓ 16 test files passed (160 tests)

Usage:

jam ask "What is 2+2?" --quiet       # just the answer
jam ask "Explain this" -q --json     # JSON only, no decorations