Replace sharp with jpeg-js + exif-reader; add bun compile binary

sharp was the only native dependency preventing a single-file binary.
Replaced with:
  - jpeg-js (pure JS) for JPEG decode/resize/encode in thumbnail gen
  - exif-reader (pure JS) for EXIF tag parsing
  - Raw JPEG APP1 marker extraction for EXIF segment discovery
  - Raw XMP packet extraction from file bytes

make build-bin produces a ~59MB self-contained Mach-O binary via
bun build --compile (bun installed via nix-shell). Zero runtime
dependencies. Tested: login, whoami, collections, files all work
from the compiled binary.

bin/quak.ts: init() called once at program start before commander
parses, so libsodium is ready for all commands including those that
restore sessions from disk.

118 tests pass.

package.json

@@ -31,7 +31,6 @@
         "@eslint/js": "9.38.0",
         "@types/libsodium-wrappers-sumo": "0.8.2",
         "@types/node": "22.18.13",
-        "@types/sharp": "0.32.0",
         "eslint": "9.38.0",
         "prettier": "3.8.1",
         "typescript": "5.9.3",
@@ -43,7 +42,7 @@
         "env-paths": "4.0.0",
         "exif-reader": "2.0.3",
         "fast-srp-hap": "2.0.4",
-        "libsodium-wrappers-sumo": "0.8.4",
-        "sharp": "0.34.5"
+        "jpeg-js": "0.4.4",
+        "libsodium-wrappers-sumo": "0.8.4"
     }
 }