Add peekaboo DPM stat to Tankopedia firepower

Adds a **Peekaboo DPM** entry nested under DPM for single-shot guns, estimating damage per minute when only firing after resetting camouflage (or waiting out the reload, whichever is slower), assuming at least 10 seconds between shots.

- Shots per minute are capped at `60/10` for reloads faster than 10s, and fall back to `60/reload` otherwise
- The result is multiplied by the currently selected shell's damage and rounded
- An (i) icon next to the label opens a popover explaining the calculation
- The row is hidden for auto-loader/auto-reloader guns
- No percentile ranking bar is shown, since no dataset exists yet for this new stat

packages/i18n/strings/en.json

@@ -631,6 +631,8 @@
             "shellRicochet": "Ricochet",
             "dpm": "DPM",
             "dpmEffective": "Effective at 60s",
+            "peekabooDpm": "Peekaboo DPM",
+            "peekabooDpmInfo": "Damage per minute assuming you only fire after resetting camouflage (or the reload finishes, if it's slower) \u2014 at least 10 seconds between shots.",
             "shells": "Shells",
             "mostOptimalShellIndex": "Most optimal shell",
             "shellReloads": "Reloads",