feat(cli): add --verbose/--quiet log-level control; reconcile improve-code-quality

[drn]

Summary

Reconciles the in-flight OpenSpec change improve-code-quality against current master + the backfilled base specs, then ships the one genuinely-remaining item and archives the change.

Finding: the proposal was ~90% already shipped. Verified against current code:

Proposal item	Reality
Replace reflection dispatch → explicit registry	✅ Already an explicit []Component slice, no reflect (base spec "Component Registry and Dispatch")
Stop discarding file-I/O errors	✅ Done (Capture warns, linkDirEntries warns, cache handles)
ioutil → os/io; remove strings.Title	✅ Zero references remain
Unit tests for pkg/cache, pkg/path, cli/is, cli/link	✅ All four _test.go files exist
go.mod → Go 1.21; go vet + staticcheck in CI	✅ Done
Atomic cache writes; Spotify device IDs via env	✅ Done
--verbose/--quiet flags	❌ Implemented here

What this PR ships

• Log-level control in pkg/log: a Level type, SetLevel/GetLevel, per-function gating, and a new Debug logger emitted only at verbose level (quiet = warnings/errors only).
• Persistent --verbose/-v and --quiet/-q flags on the root command (--quiet wins on conflict), applied via PersistentPreRun.
• Unit tests for the gating behavior.

OpenSpec reconciliation

• Rewrote proposal.md Why/What to stop claiming reflection/ioutil/no-tests and list what already shipped.
• Reduced the cli-framework delta to the one new requirement (Log Level Control); dropped requirements already present in the base spec.
• Intentionally dropped "return errors instead of os.Exit" and "Capture returns an error" — these contradict the shipped, now-spec'd "Process-Exit Error Model" and "Command Execution Helpers" base requirements. They're a redesign, not unfinished work; revisit via a separate proposal if desired.
• Archived the change into specs/cli-framework within this PR (per repo policy).

Verification

go install ./..., go vet ./..., go test ./..., revive, staticcheck, bash .github/skill-tests/run_all.sh (26/26), bash .github/lint-skills.sh, npx agnix@0.13.0 . (0 errors), qlty smells — all green. openspec validate --specs --strict passes. (qlty check's radarlint-go plugin hit an environmental internal LSP error; CI runs qlty with --no-fail.)

🤖 Generated with Claude Code

Co-Authored-By: Claude noreply@anthropic.com