research: read what a node costs, unlocks and does

The research tree spoke only the node's name and whether you could afford
it. Everything that tells you whether it is worth affording -- the
knowledge cost, the recipes it unlocks, the description -- is drawn in
the hint windows beside the tree and was never spoken, so "cannot afford"
gave no way to find out what was missing or by how much.

states/research.lua now implements details(), the same = / Shift+= hook
the item grids use: cost with the shortfall spelled out, what it unlocks,
then the description, one block each so [ and ] walk them back. Shift+=
adds the name line and the whole knowledge purse across all four types.
The focus line also takes its name from the node's title instead of
humanising the id, so it is "Sewing techniques", not "sewing techniques".

Everything is read from the state's currentNode upvalue -- the display
table updateCurrentNode() assembles for the hint window -- rather than
models/research.lua, whose nodes table is file-local and whose unlocks
are recipe ids, which would have named the recipe instead of the item it
produces. The shortfall is computed against journalModel.knowledge,
required lazily because models.journal drags in much of the game.

The tree has no hotkey and the prologue may hold no writing desk, so the
testbed enters it the way the desk does: ingame.interface("research"),
the exact call in the desk's tryInteractFunction. Require it as
"states/ingame" and not "states.ingame" -- states.lua uses the slash
form, and the dot form loads a second copy of the module whose
levelWindow is nil, which research.draw indexes on its first frame.

98 testbed checks, 0 failures.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

accessibility/details.lua

@@ -28,9 +28,9 @@
 -- the detail text back afterwards -- the same trick states/journal.lua uses for
 -- journal pages. A long description therefore never has to be caught first time.
 --
--- Implemented so far by the four item-grid screens (_itemgrid.lua). Any other
--- descriptor can gain it for free: research nodes and examine-mode tiles are the
--- obvious next ones.
+-- Implemented by the four item-grid screens (_itemgrid.lua) and by the research
+-- tree (states/research.lua). Any other descriptor can gain it for free:
+-- examine-mode tiles are the obvious next one.
 
 local speech = require("accessibility.speech")
 local history = require("accessibility.history")