Add human-readable sector names

[atomantic]

Players previously navigated by raw sector numbers. This PR gives every sector a human-readable name, flows it through the server, agents, and client, and lets tool calls accept either an ID or a name.

Naming scheme

5000 unique names, deterministic (seed=42), drawn from 200 adjectives × 200 nouns with sci-fi flavor (Quantum, Pulsar, Orion, Kepler, Plasma, Hyperion, Aether, Nexus, etc.). ~65% are two-word, ~35% are three-word. Max token reuse is 61 out of 5000 names; 399 of 400 tokens appear at least once.

Two-word samples: Flux Gorge, Lost Aether, Infinite Network, Nebula Ingress, Deep Kessel, Hex Causeway, Iron Magnet, Echo Reach

Three-word samples: Photon Midnight Passage, Sapphire Sleeping Rampart, Rusted Royal Remnant, Jade Barren Path, Lazuli Drifting Sound, Searing Oblivion Nexus, Liminal High Ravine

Megaport grand names (applied at load time from meta.mega_port_sectors, cycled if a universe has more megaports than entries): Grand Nexus Station, Federation Prime Hub, Galactic Gateway, Sovereign Command, Imperium Bastion, Core Meridian

Changes

• universe_structure gains a name column; idx_universe_structure_name_lower indexes LOWER(name) for case-insensitive resolution
• scripts/generate_sector_names.py seeds the 5000 unique names; generator is universe-agnostic so megaport IDs can differ per environment
• load_universe_to_supabase.py applies megaport grand names at load time based on universe.meta.mega_port_sectors
• SectorSnapshot, LocalMapSector, MapSectorNode carry name to the client; new formatSectorLabel util used in banner, sector panel, and map-node popover
• New resolveSectorParam(pg, payload, key) replaces per-caller sector-name resolution boilerplate in move, plot_course, path_with_region, local_map_region, combat_action
• Agent tool schemas accept ["integer", "string"] for sector params; voice/task prompts teach the "ID - Name" display format
• Fixes pre-existing pgClient connection leaks in plot_course, path_with_region, local_map_region, combat_action by adding finally { pgClient.release(); } symmetric to the move handler pattern

[jptaylor]

@atomantic really nice. Fun to think about how we could support sector naming in the future, once your corporation has enough interests in a space.

Will give this a good test before merging (thinking about critical-path database queries where index speed matters) but excited to do it.

We'll also need to think of a way of updating current world data, so we can migrate without a reset. Should be simple enough!

[atomantic]

whoops, accidentally bundled another idea into this PR. will split into two.

[atomantic]

I'm not particular about these names just thought it was a fun stab so feel free to go with a different set when you review this idea or implement it a different way :)