feedback1d WO: the preference route is 0.1.0's again; equal floor keeps the official route

Review follow-up to the D5 fix. Two changes in grid.js _buildField:

- The road-over-floor preference smoothing is 0.1.0's again: its line of sight
  may cover non-blockable tiles (Bresenham footprint, diagonal-step corners
  included) only on the tile's own raw chain, and the jump stops at the first
  ancestor it cannot see so. Exact crossings (a corner touch is not a crossing)
  are used only to choose between the official and the preference pointer.
  The previous version let the preference brush the corner of off-chain floor,
  so on 战场#02's Final Assault the right-half exit route (2,10) -> (3,11)
  slipped past an operator on (2,11) while the left half was still blocked on
  (2,9). Both halves now mirror each other again ((2,10) -> (2,11) -> (4,11)).
- On an equal floor count the official pointer stays; the preference pointer
  wins only when it merely skips a collinear official waypoint (same walk).
  The old "farther waypoint" tie-break could bend an official route without
  saving any floor, e.g. a crate on (10,6) of 战场#04 brought back the L via
  (9,8) for the lower gate.

Still 140 of 154 stage routes official; data/stages.json groundPaths
regenerated (战场#02 boss right exit back to 0.1.0's, device-less helper paths
of #03 / #04 / #06 follow the same rule). New tests: 战场#02 boss exits mirror
and are blocked beside the exit; a single crate on any tile of an active stage
never leaves a gate route non-official without crossing strictly less floor.
The cross-check reference port follows both rules.

docs/research/08-waves-official.md

@@ -349,13 +349,14 @@ The raw BFS chains and smoothed waypoints are in scratch `lanes_official.txt`.
 
 **Remake deviation (user playtest #2, 2026-09-29; narrowed after the community report D5, 2026-10-03).** The user
 reported the 战场#01 lower-gate enemies walking up the col-9 floor lane, where no operator can block them.
-`server/sim/grid.js` keeps every official route LENGTH and the official route itself unless a road-over-floor
-preference route (equal-length ties to the chain with the fewest non-blockable floor / gate tiles, smoothing that never
-cuts across floor its grid route does not walk) crosses fewer non-blockable tiles; a segment that only touches a floor
-tile's corner does not cross it. The first version (2026-09-29) counted those corner tiles as crossed and so also bent
-official diagonals into L shapes — the D5 report after 0.1.0: on 战场#04 the lower-gate enemies walked (9,10) → (9,8)
-→ (10,8) instead of the official diagonal (9,10) → (10,7), which only brushes the corner of the floor (10,9). Lanes that
-still differ from the table above (14 of the 154 stage × gate × field routes, test/sim/pathing-official.test.js):
+`server/sim/grid.js` keeps every official route LENGTH and the official route itself unless the 2026-09-29
+road-over-floor preference route (equal-length ties to the chain with the fewest non-blockable floor / gate tiles,
+smoothing that never cuts across floor its grid route does not walk, the corner tiles of a diagonal step included)
+crosses strictly fewer non-blockable tiles; in that comparison a segment that only touches a floor tile's corner does
+not cross it. Used alone (0.1.0) the preference also bent official diagonals into L shapes — the D5 report after
+0.1.0: on 战场#04 the lower-gate enemies walked (9,10) → (9,8) → (10,8) instead of the official diagonal (9,10) →
+(10,7), which only brushes the corner of the floor (10,9). Lanes that still differ from the table above (14 of the 154
+stage × gate × field routes, test/sim/pathing-official.test.js):
 - act1 m01 #01, lower gate: (9,10) → (9,8) → **col 8 road up** → (12,8) → row 12 → col 4 → E (official: (9,9) → (12,8)
   through the floor (10,9)); the 联防 partner routes pass the same exit.
 - Boss fields: the exits from (2,10) on 战场#01 / #02 avoid part of the arena's central floor; 战场#02's 联防 partner
@@ -363,6 +364,11 @@ still differ from the table above (14 of the 154 stage × gate × field routes,
   Floor the terrain forces stays (gates, (12,9) beside the upper gate, the col-9 floor where walls or a crate block the
   road: #02 lower (10,9)/(11,9), #04 upper (11,9), #05 upper (11,9)/(10,9), #07 lower (10,9)).
   Full audit: test/sim/pathing-blockable.test.js.
+- Official again since D5 (0.1.0 took L routes there): 战场#04's lower gate (normal, 联防) and boss exits, the boss exit
+  (5,10) of 战场#05(下半), the boss exit (2,10) of 战场#07(下半) and the inactive 战场#06(上半). The diagonal first
+  step out of the (2,10) exit of 战场#07(下半) (and #06(上半)) passes its side tiles (2,9) / (2,11) at exactly
+  √0.5 ≈ 0.70711, just beyond the ground block radius 0.70709997 (PRTS 游戏数据基础 §阻挡半径), so an operator standing
+  there no longer catches those enemies; every other blocking tile of the 154 routes is unchanged.
 
 ### 3.3 What we do and the root cause of "upper-gate enemies walk the lower lane"