1.4.271 — Yellow frame-rate candidate (perf port)

Yellow frame-rate test candidate, built from the v10 api3 prototype Gen-1 perf pass ported onto 1.4.270.

What changed (only 3 files vs 1.4.270: lib/KantoMain.lua, lib/KantoRoutines.lua, manifest.json):

• Cached option reads (optCached, 0.5s cache) instead of per-NPC-per-frame option walks
• Sleep scan, new-NPC scan, and dsSpecies stamp throttled to twice a second
• Terrarium mod lookup memoized; settings pushed only when they change
• Travelling-NPC scan now checks only flagged NPCs instead of every NPC
• No NPC behaviour changed; force and map-change scans still run immediately

Verification: boot-verified on gen1recomp 0.3.96 in all 3 gens, zero Lua errors (Yellow, Gold, FireRed).

Honest limit: the boot rig cannot measure frame rate, so the Yellow fps improvement is UNPROVEN until an in-game play-test. If Yellow still drops frames with this build, please report back — the cause is something else and we will need profiling data from that session.

Includes the 1.4.270 Emerald fix (native NPCs no longer hijacked as random NPCs). Does NOT include the uncommitted travel-forcing / Gen 3 trade work still in the main tree.