Big fix wave: hub walking instant, alchemy/quest popup cleanup, hero-died + last-resort tutorials

Hub walking is instant. Per #294, tapping a trigger in the base now fires it immediately instead of requiring the hero to walk over the spot first. The walk-over wait was a small constant tax that added up across a session.

Alchemy ingredient rows behave better. Per #292, the whole row used to redirect into Alchemy, which collided with row selection. A dedicated Alchemy button now lives on the row, so taps go where you expect. And per #304, ingredient counts color green when you have enough and red when you don't — sufficiency reads at a glance instead of requiring mental math.

Two confirm-and-don't-lose-your-work fixes. #296: leaving a story fight from the VS popup now asks for confirmation, so you don't accidentally back out of a fight you meant to start. #320: the Plan Ready popup no longer discards your plan when you tap outside the popup — backdrop tap was treated as cancel, which silently threw away the planned turn.

Two new client tutorials. #299 adds a hero-died tutorial that fires the first time a hero falls in combat. #303 adds a last-resort tutorial for the late-fight state where you're down to a single hero. Both plug gaps where players were left guessing at what to do.

Sigil descriptions are now playable copy. The placeholder text on sigils — "this is a sigil description" style filler — is replaced with descriptions that actually tell you what the sigil does. Spell crafting reads as a real system instead of a stubbed one.

Two smaller bugs cleaned up. Tutorial turn 1 used to wipe a recorded cast when a move was re-seeded; now the cast survives the move change. And story-scene exits attach a targetSceneId via #321, fixing the broken-bridge quest flow where the exit didn't know where to send you.