fix: complete v5 routing — API exposure, rescore persistence, leverage cap, key backup doc

Three plumbing fixes + one ops doc that close the gaps from the audit.

scripts/rescore_v5.py
  Was overwriting only signal/conf/reasoning/sentiment/relevant/
  prefilter_reason/analysis_version. Now also persists target_asset,
  category, expected_move_pct — without these the bot can't route
  rescored posts correctly (would silently fall back to BTC).

app/schemas.py + app/api/posts.py
  TrumpPost response model didn't expose target_asset/category/
  expected_move_pct, so the frontend had no way to display "this
  signal will trade SOL". Added the three fields + mapping in
  _post_to_schema(). Pre-v5 posts return null. No frontend changes
  yet — display work is a follow-up.

app/services/hyperliquid.py
  HL caps max leverage per asset (BTC/ETH 50×, SOL 20×, memes 3-5×).
  set_leverage() always tried to push self._leverage — if user set
  30× and bot routed to TRUMP, HL rejected the order and the trade
  silently dropped. Added _get_max_leverage() (queries meta()'s
  maxLeverage field) and _clip_leverage() that caps to HL's max.
  set_leverage now returns the effective leverage so callers can
  use it for notional sizing if needed.

deploy/ENCRYPTION_KEY_BACKUP.md
  Documented mandatory backup procedure for the symmetric key that
  encrypts every user's HL API key. Lost key = all users' bots dead
  with no recovery. Includes rotation procedure + quarterly test
  step + things-not-to-do list.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/schemas.py

@@ -30,6 +30,13 @@ class TrumpPost(BaseModel):
     analysis_version: Optional[str] = None
     relevant: bool
     price_impact: Optional[PriceImpact] = None
+    # v5 asset routing — what the bot will actually trade if signal != hold.
+    # target_asset = any HL perp ticker (BTC/ETH/SOL/TRUMP/...). category
+    # buckets the post's catalyst type. expected_move_pct = AI's own 1h-move
+    # estimate on target_asset. All three are null on pre-v5 posts.
+    target_asset: Optional[str] = None
+    category: Optional[str] = None
+    expected_move_pct: Optional[float] = None
 
     model_config = {"from_attributes": True}