feat(bots): promote gen5 stage-5 policy to the Hard tier

Hard has been a label-only duplicate of medium.json since medium was promoted
on 2026-08-17. Promote 20260823-1734-gen5-s5-intercepts-retry2 into
hard.json so the tier is a genuinely distinct policy, and so the strongest bot
the curriculum has produced survives the next round's checkpoint pruning —
promoted files are never touched by training scripts.

Stage 5 blocked after three attempts, so like medium.json this comes from a run
recorded as decision: "fail". Both failing floors are covered in TRAINING.md:
goal_rate 0.7369 vs 0.75 is marginal, and productive_air_touch_fraction 0.0001
vs 0.005 is a bar no policy in the lineage has approached, against a metric
quantised at 0.01 per ~100-episode window. On every other axis it is the best
yet: upright_fraction 0.757 against a 0.40 floor that the pre-Round-6 lineage
never pushed past 0.331, and forward_motion_fraction 0.479 against 0.20.

Chosen over attempt 2 (retry1) on a tiebreak, not a margin. retry1 posts a much
wider indirect result against medium.json (63-23-14 vs 47-32-21), but a direct
100-episode head-to-head between the two finished 36-39 with 25 draws, so that
gap does not reflect a real strength difference. Attempt 3 is the later
checkpoint (it resumed from attempt 2) and edges every telemetry metric.

Verified: hard.json is byte-identical to its source export, matches easy/medium
on input_size 83, 3 layers and action space, and beats medium.json 19-7-4 in a
fresh 30-episode paired run. Tiers stay monotonic: hard > medium > easy.

That head-to-head also showed a 17% physical side imbalance (physical teams
0-1 = 29-46), reproduced at 13% in the 30-episode check. Inside the 20% bar
used elsewhere and equal across both models, but noted in TRAINING.md as worth
investigating rather than assuming variance.

TRAINING.md

@@ -181,12 +181,36 @@ promoted file is never touched by training scripts, never overwritten by a
 same-named future export, and never disturbed by pruning old experiment
 files from the flat dump.
 
-Easy and Medium are now genuinely different policies. Hard still points at
-`medium.json` and remains a label-only duplicate until a stronger policy earns
-`hard.json`. Every tier runs at full trained cadence (`reaction_ticks=8`,
-`action_noise=0`) — the game does not manufacture difficulty gaps by
-handicapping a model. When promoting, keep the tiers monotonic: a lower tier
-must never point at a policy that beats the tier above it.
+`hard.json` was promoted 2026-08-24 from generation 5's
+`20260823-1734-gen5-s5-intercepts-retry2` — Stage 5 attempt 3, and like
+`medium.json` above it is recorded as a *fail* in `generation5_state.json`.
+Stage 5 blocked after three attempts on two telemetry floors: `goal_rate`
+0.7369 against a 0.75 bar (marginal), and `productive_air_touch_fraction`
+0.0001 against 0.005. The second is not a judgement about this policy — see
+"Generation 5" below — the metric is quantised at 0.01 (one touch per ~100
+episode logging window), so a 0.005 floor demands a productive air touch in
+half of all windows, and no policy in the lineage has ever come close. On
+everything else it is the strongest bot produced so far: `upright_fraction`
+0.757 against a 0.40 floor (the pre-Round-6 lineage never exceeded 0.331),
+`forward_motion_fraction` 0.479 against 0.20, and it beats `medium.json`
+47-32-21 over 100 paired episodes.
+
+Attempt 2 (`20260823-0258-gen5-s5-intercepts-retry1`) posts a much wider
+margin against `medium.json` (63-23-14) and was the obvious alternative, but a
+direct 100-episode head-to-head between the two finished 36-39 with 25 draws —
+a dead heat, so the wider indirect margin does not reflect a real strength
+difference. Attempt 3 was taken on the tiebreakers: it is the later checkpoint
+(it resumed from attempt 2) and edges every telemetry metric. That head-to-head
+also measured a 17% physical side imbalance (physical teams 0-1 = 29-46, with
+`retry1` going 15-25 as team 0 but 21-14 as team 1) — inside the 20% bar used
+elsewhere, but large enough to be worth understanding rather than assuming it
+is noise, since it affects both models equally and may point at an asymmetry in
+the arena or in `ship_observations.gd`'s team-1 mirroring.
+
+Every tier runs at full trained cadence (`reaction_ticks=8`, `action_noise=0`)
+— the game does not manufacture difficulty gaps by handicapping a model. When
+promoting, keep the tiers monotonic: a lower tier must never point at a policy
+that beats the tier above it.
 
 To promote a new bot into a tier: copy the chosen `Game/bots/<experiment>.json`
 to `Game/bots/promoted/<tier>.json` (overwriting the old one), and note the