fix(game): restore exact media thresholds

Replace the inferred exponential media progression with the four initialized
32-bit thresholds used by the original score-addition path: 140,000, 650,000,
1,300,000, and 4,000,000. Award exactly one media level and extra ball at each,
with no nonexistent fifth tier.

Test Plan:
- `cargo test --all-targets` -- 50 passed
- `cargo clippy --all-targets -- -D warnings` -- passed
- `cargo build --profile production` -- passed
- threshold boundary and four-extra-ball test -- passed
- `git diff --cached --check` -- passed

original/MECHANICS_PROGRESS.md

@@ -189,3 +189,9 @@ per-player effect word, and activated type-4 record 149. `1000:c4e1` maps effect
 1-5 to 10,000, 20,000, 50,000, 100,000, and 200,000 bonus; effect 6 transfers
 the accumulated bonus to score. Entering record 149 also awards its static 500,
 clears the selection, and disables the record until line 84 is hit again.
+
+The score-addition path at `1000:bc36` indexes the initialized 32-bit threshold
+table at DGROUP `0x825` using media state 1-4. The exact thresholds are 140,000,
+650,000, 1,300,000, and 4,000,000. Crossing each threshold increments the media
+state and remaining-ball count; the apparent fifth table word is the next
+unrelated global, not a fifth media tier.