Seven real-bug fixes called out across review comments on merged PRs:

- pkg/platform/platform.go: resetLookPathCache() no longer reassigns
  the package-level sync.Map (unsafe vs concurrent readers). Uses
  Range+Delete instead.
- pkg/installer/providers/brew.go: GetLatestVersion no longer caches
  context-canceled / deadline-exceeded errors. A caller with a short
  ctx would have poisoned the 5m TTL for every later caller.
- pkg/installer/providers/progress.go: the progress writer is now
  wrapped in a locking writer so concurrent Write calls from
  cmd.Stdout and cmd.Stderr (os/exec writes those from separate
  goroutines) don't interleave bytes mid-call.
- pkg/catalog/embed.go: EmbeddedJSON() now returns a copy of the
  backing bytes. Previously callers could mutate the package-level
  []byte, corrupting the baseline for every future Get().
- pkg/catalog/manager.go: loadEmbedded now also probes
  /usr/share/agentmgr/catalog.json — where the goreleaser nfpm
  config installs the catalog for .deb/.rpm users. Previously that
  path was silently ignored at runtime even though goreleaser wrote
  the file there at install time.
- internal/cli/doctor.go: Catalog Sources section updated with the
  matching /usr/share/agentmgr row so `doctor` output mirrors the
  loader's probe order.
- internal/cli/agent.go: removed the --all (-a) and --check-updates
  flags from `agent list`. Both bound to local vars that were never
  read anywhere, so the flags did nothing; users setting them got a
  silent no-op instead of a useful behavior.

Supersedes the corresponding Copilot annotations on PRs #19, #28,
#29, #33, plus the dead-flag note on the agent list command.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Batch of small review-comment fixes — documentation accuracy, test
hardening, and gosec G104 on grpc teardown:

- pkg/api/grpc/server.go: explicit \`_ = s.listener.Close()\` in Stop()
  and ForceStop() with a comment noting the close error is not
  actionable during teardown (silences gosec G104).
- pkg/catalog/manager.go: Refresh doc now explicitly notes that
  singleflight does not merge contexts and the first caller's ctx
  governs the shared fetch — a caller with a short deadline can
  cancel the in-flight work for all shared callers.
- pkg/installer/providers/progress.go: WithProgressWriter doc clarifies
  why passing nil is a no-op (asymmetry lets middleware attach a writer
  safely without downstream code accidentally clobbering it).
- internal/systray/cli_uninstall_darwin.go: file is darwin-only via
  //go:build tag, so platform.ID() is always Darwin at runtime. Removed
  the dead Linux and Windows branches (the filepath/os/platform imports
  they needed are gone too).
- CHANGELOG.md: "(Removed in [Unreleased].)" was a broken shortcut
  reference link — promoted to "(Removed in v1.2.0.)".
- README.md: feature bullet uses the full "agentmgr agent list" command
  prefix, consistent with everywhere else in the doc.
- internal/cli/output/spinner_test.go: non-TTY test replaced the
  30ms sleep with a direct assertion on s.isTTY. Start() is a no-op
  when isTTY is false, so sleeping was measuring nothing.
- internal/cli/output/table_test.go: ANSI-alignment loop now actually
  asserts inter-column padding instead of discarding each line.
- internal/systray/handlers_test.go: mustParseVersion panics on parse
  error so test-setup bugs surface at the fixture, not downstream.
  TestDialogTracking uses bare *exec.Cmd values (trackDialog only
  checks pointer identity) to avoid the PATH lookup for \`true\` on
  Windows CI.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>