feat(cli): implement watch command with fsnotify and --json streaming

[abhinav-1504]

What

Implements optiqor watch [chart] — re-analyzes a Helm chart or
values file whenever a YAML file changes.

Why

Fixes #15

How

• internal/watch/watch.go — core watch loop using fsnotify; 200ms
  debounce to absorb editor save storms; ANSI screen clear between
  runs when stdout is a TTY; --json streams newline-delimited JSON
  events (start/update/error); SIGINT/SIGTERM → clean exit (code 0)
• cmd/optiqor/main.go — wired newWatchCmd() to call watch.Run();
  added --json flag; honours --no-color and NO_COLOR
• Tests use context cancellation instead of OS signals for
  cross-platform compatibility

Testing

• go test ./internal/... ./pkg/... -timeout 30s — 10/10 PASS
• go build ./... — clean
• Tested locally:
  • optiqor watch ./cmd/optiqor/demo/values.yaml → full report, waits
  • optiqor watch ... --json → valid JSON streamed
  • File change → update event emitted
  • Invalid YAML → error event emitted gracefully
  • Ctrl-C → exits with code 0

Note: TestGolden in cmd/optiqor fails on Windows only due to
path separator differences (\ vs /) — pre-existing issue unrelated
to this PR. CI runs on Ubuntu where it passes.

Checklist

• PR title follows Conventional Commits
• All commits are DCO-signed
• No unrelated changes pulled in
• No LLM calls or telemetry introduced
• No proprietary backend imports

[github-actions]

First PR — welcome aboard!

A few things to expect:

1. CI: every PR runs build + race tests + lint on Ubuntu and macOS. If something fails, the log will tell you exactly which gate.
2. DCO: every commit needs Signed-off-by:. git commit -s adds it automatically.
3. Conventional Commits: PR titles like feat(analyze): new rule or fix(cli): handle X. We squash-merge by default.
4. Review: a maintainer will review within 72 hours. Suggestions are conversations, not orders — push back if something doesn't fit your context.

If you get stuck, reply here or jump to Discussions. We want this PR to land.

[abhinav-1504]

Hello @btwshivam,
All CI checks now passing — race condition fixed with mutex-protected safeBuffer, lint issues resolved (nolint explanation, context parameter order, removed unused notYetImplemented).

[abhinav-1504]

Hi @btwshivam, just following up on this PR. All CI checks are passing now and the latest changes have been pushed.

Could you please take another look when possible? Thanks.