Harden canvas state isolation for neon HUD and ship rendering

[serzel]

Motivation

• Prevent HUD neon rendering state (shadowColor, shadowBlur, globalCompositeOperation, globalAlpha) from leaking into ship rendering when save()/restore() nesting is imbalanced.
• Make neon drawing paths robust against surrounding code that may mis-manage canvas state so visuals (weapon halo) always reflect game state, not residual HUD state.
• Ensure Ship.render() never inherits composite or shadow settings from prior UI draws.

Description

• Added resetRenderIsolationState(ctx) and withNeonIsolation(ctx, draw) to src/ui/neon.js and applied them to tubeStroke, neonLine, neonPanel, neonText, and neonBar so every neon draw path explicitly resets state before and after drawing.
• Replaced ad-hoc save()/restore() usages inside neon code with the isolation wrapper and explicit resets to guarantee ctx.shadowBlur = 0, ctx.shadowColor = 'rgba(0,0,0,0)', ctx.globalCompositeOperation = 'source-over', and ctx.globalAlpha = 1 on exit.
• Refactored Ship.render() in src/entities/Ship.js to add a local resetRenderState() and to wrap trail, sprite, thrust, and halo sections with try/finally blocks and explicit resets so ship drawing begins and ends with a known clean canvas state.

Testing

• Ran node --check src/ui/neon.js and it succeeded.
• Ran node --check src/entities/Ship.js and it succeeded.
• Attempted an automated page render/screenshot (Playwright) but the local HTTP server startup failed in this environment and the Playwright run returned net::ERR_EMPTY_RESPONSE, so the visual smoke test did not complete.

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Codex Task