Surface unmanaged .app bundles during sync as Markdown report

`ssr sync` now scans /Applications (and ~/Applications, configurable via
SSR_APP_DIRS) for top-level .app bundles that are neither Mac App Store
installs (Contents/_MASReceipt/receipt) nor Homebrew Cask installs, and
writes <backup_dir>/unmanaged-apps.md alongside the Brewfile. This closes
a long-standing gap in the restore story: such apps need manual reinstall
on a fresh machine, and were previously invisible to the sync workflow.

Cask detection runs fully offline against the local Caskroom and unions
four complementary strategies:

  1. Caskroom walk for .app symlinks/bundles under
     $(brew --caskroom)/<cask>/<version>/.
  2. `app "Foo.app"` declarations parsed from .rb formula receipts.
  3. `name "Foo"` field from .rb receipts (handles pkg-based casks like
     Microsoft Edge, Teams, Zoom, Google Drive, etc., that never drop
     a .app under the caskroom).
  4. `"name":["Foo"]` field from modern .json receipts (multi-line aware).

For each unmanaged app the report includes version and bundle id from the
Info.plist plus a best-effort installer link, in preference order:

  1. Sparkle SUFeedURL → derive the vendor homepage from the URL host.
  2. Bundle-id prefix match against a curated vendor map (Adobe,
     Microsoft, Docker, Cursor, Anthropic, OpenAI, JetBrains,
     GitKraken, Signal, Zoom, Telegram, Slack, Synology, Jabra, ...).
  3. DuckDuckGo search fallback (`<App name> macOS download`).

Toggles in ssr.conf.example: SSR_SCAN_UNMANAGED_APPS=true (default),
SSR_APP_DIRS=/Applications:~/Applications.

ssr-status gains a one-line summary referencing the report file.

Co-authored-by: Cursor <cursoragent@cursor.com>

config/ssr.conf.example

@@ -22,6 +22,16 @@ SSR_MACKUP_SUBDIR=Mackup
 SSR_BREW_UPGRADE=true
 SSR_BREW_CLEANUP=true
 
+# ---------------------------------------------------------------------------
+# Unmanaged-app scan during sync
+# ---------------------------------------------------------------------------
+# Lists .app bundles installed manually (not via brew cask, not via MAS).
+# Writes <backup_dir>/unmanaged-apps.txt for restore-time reference.
+SSR_SCAN_UNMANAGED_APPS=true
+
+# Colon-separated directories to scan (top level only).
+# SSR_APP_DIRS=/Applications:$HOME/Applications
+
 # ---------------------------------------------------------------------------
 # macOS restore behavior
 # ---------------------------------------------------------------------------