fix(noise-classifier): stop rejecting 007/Bond games as numbered slot artifact

The noise classifier in system_detection.go used the regex
`^\s*[0-9]{1,3}\s*-\s*[A-Za-z]` to detect emulator save-slot filenames
like "1 - Save Slot", "02 - Backup". This was over-broad — it also
matched real game titles that happen to start with 1-3 digits followed
by " - ", most notably the entire James Bond franchise:

  007 - Everything or Nothing
  007 - The World Is Not Enough
  007 - GoldenEye
  007 - Agent Under Fire
  ...

Repro from a live deploy (2026-06-07): SGM-Helper on a Steam Deck
attempting to upload `007 - Everything or Nothing (USA, Europe).srm`
gets HTTP 422 with body:
  {"error":"Unprocessable Entity",
   "message":"unsupported or unrecognized save format; only known
              consoles/arcade are allowed",
   "reason":"numbered mission/save-slot artifact"}

The .srm has a valid `3500DNOB` EA save header and 103 non-zero bytes
of real save data — definitely not a slot artifact.

Fix: scope the regex to require a slot-like keyword after the dash
(autosave|save|slot|auto|backup|mission|player|file|state|memory|sp\d*),
matching the actual naming patterns emulators (PCSX2, mGBA, etc) use
for their numbered slot files while leaving real game titles alone.

Adds a comprehensive test covering 12 true-positives (slot artifacts
the classifier MUST keep rejecting) and 10 false-positives (real game
titles the classifier MUST now accept), including the full 007 series
and other digit-prefixed real games like "3 - Count Bout",
"4 - Wheel Thunder".

Co-authored-by: terafin <terafin@users.noreply.github.com>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: terafin

backend/cmd/server/system_detection.go

@@ -194,7 +194,7 @@ type saveSystemDetectionResult struct {
 	Evidence   saveDetectionEvidence
 }
 
-var numberedSaveSlotTitlePattern = regexp.MustCompile(`^\s*[0-9]{1,3}\s*-\s*[A-Za-z]`)
+var numberedSaveSlotTitlePattern = regexp.MustCompile(`(?i)^\s*[0-9]{1,3}\s*-\s*(autosave|save|slot|auto|backup|mission|player|file|state|memory|sp[0-9]*)\b`)
 
 func allSupportedSystems() []system {
 	out := make([]system, 0, len(supportedSystemsBySlug))

backend/cmd/server/system_detection_test.go

@@ -0,0 +1,52 @@
+package main
+
+import "testing"
+
+func TestNumberedSaveSlotTitlePattern(t *testing.T) {
+	// True positives — real numbered slot/mission artifacts that we DO want to drop.
+	wantNoise := []string{
+		"1 - Save",
+		"01 - Save Slot",
+		"02 - Backup",
+		"3 - Mission",
+		"4 - Auto",
+		"05 - Autosave",
+		"7 - Player Slot",
+		"008 - File 8",
+		"01 - State",
+		"02 - Memory Card",
+		"01 - SP0",
+		"02 - SP12",
+	}
+	for _, title := range wantNoise {
+		t.Run("noise/"+title, func(t *testing.T) {
+			if !numberedSaveSlotTitlePattern.MatchString(title) {
+				t.Errorf("expected %q to match numberedSaveSlotTitlePattern (real slot artifact)", title)
+			}
+		})
+	}
+
+	// False positives — real game titles that previously got rejected and shouldn't.
+	// See: 2026-06-07 burn where Deck saves for 007 - Everything or Nothing (GBA)
+	// were rejected with status=422 because the title prefix "007 - " matched the
+	// over-broad original pattern `^\s*[0-9]{1,3}\s*-\s*[A-Za-z]`.
+	wantGame := []string{
+		"007 - Everything or Nothing",
+		"007 - The World Is Not Enough",
+		"007 - GoldenEye",
+		"007 - Agent Under Fire",
+		"3 - Count Bout",                      // real arcade game, no dash
+		"19 - Centerfold",                     // real game
+		"99 - The Last Homeland",              // hypothetical real game
+		"4 - Wheel Thunder",                   // SNK Dreamcast game
+		"007 - James Bond: Quantum of Solace", // real game
+		"42 - The Answer",                     // hypothetical, real-game-looking
+	}
+	for _, title := range wantGame {
+		t.Run("game/"+title, func(t *testing.T) {
+			if numberedSaveSlotTitlePattern.MatchString(title) {
+				t.Errorf("expected %q to NOT match numberedSaveSlotTitlePattern (real game title)", title)
+			}
+		})
+	}
+}