Add Isafdar navigation obstacles and Lletya content

[HarleyGilpin]

Adds the interactable objects needed to navigate Isafdar and the missing Lletya content, plus a crystal bow combat fix found while testing.

Isafdar navigation

• Dense forest passages (3937-3939, 3998/3999) - squeeze through with rotation-aware movement; the two Elf Camp passages require 56 Agility (data-driven level param). Players line up with the tile nearest the passage centre before squeezing through.
• Tripwire (3921) / sticks trap (3922) - step-over with an agility success roll; failure deals damage with authentic messages.
• Leaf traps (3923-3925) - jump across on click; failing the roll or walking onto the trap tile drops the player into the pit below (spikes damage), with the protruding rocks (3927) to climb back out. All four trap sites wired to their pits.
• Log balances (3931/3932/3933) - 45 Agility, 7.5 xp. Approach is interruptible by walking away; the crossing itself is done at walk speed with the rope balance render emote.
• Elven Overpass rocks (9296/9297) - three cliffside shortcuts at 59/68/85 Agility.
• Lletya tree entrance (8742) - gated on Roving Elves.
• Arandar heavy gates (3944/3945), Underground Pass door pass-through (4006/36000) and Poison Waste caves/sewer ladders (until the full dungeon content exists).

Lletya

• Teleport crystal - Activate teleports to Lletya using the existing charge degrade chain, with degradation messages.
• Eluned - re-enchants uncharged crystals for 750 coins, decreasing by 150 per recharge to a floor of 150 (persisted per player).
• Islwyn - sells new crystal bows/shields for 900,000 and attunes crystal seeds for 900,000 decreasing by 180,000 to a floor of 180,000 (persisted per player).
• Shopkeeper dialogues (Eudav, Oronwen, Dalldav, Gethin) opening their existing shops, and flavour dialogue for Goreu, Ysgawyn, Mawrth, Arvel, Kelyn, Eoin, Iona and Gwir.
• Elf musician (8723) no longer turns to face players (interacts = false), staying locked facing south.

Fixes

• Crystal bow dropped itself as ammo: new_crystal_bow didn't match the startsWith("crystal_bow") check in ammo/Ammo.kt, so firing it removed the bow from the weapon slot and dropped it at the target like a thrown weapon. Now maps to the same no-ammo handling as the rest of the chain.
• objectApproach supports arrive = false (mirroring objectOperate): approach handlers can now run without waiting for the already-queued route to finish. Needed because the log balance's cache reach tile is south of the log - without this the player always detoured a tile south before crossing.

Notes

• Trap fail damages and success rates are placeholder values flagged with TODOs; exact 2011 numbers are unverified.
• Which pit belongs to the west/centre/north leaf traps is a best guess (the south trap's pit is verified); flagged in code.
• Quest gates use questCompleted("roving_elves"), relying on quests.requirements.skipMissing until the elf quests are implemented.

Testing

• IsafdarTest (17 tests): every obstacle type, level gates, trap failure damage, pit fall/climb-out, log pathing regression (7 start positions asserting no south detour), approach interruption.
• LletyaTest (6 tests): teleport crystal charge chain, Eluned/Islwyn price ladders and persistence, shopkeeper dialogue opening shops.
• CrystalBowTest: bow stays equipped and degrades correctly when fired.
• Full :game: and :engine: suites pass.

[Ebp90]

I can convert Regicide, Roving Elves and MEP1 to compliment this at some point.