Implement all improvements.md runtime/config refactors in packaged mod source - #3

This PR applies the full set of improvements documented in improvements.md to the mod implementation shipped in Knockback_Mod_v1.0.0.zip. The update focuses on safer config handling, lower per-activation overhead, cleaner physics timing, and clearer plugin metadata/runtime behavior.

• Config + metadata hardening

  • Added bounded config entries for knockback force/radius via AcceptableValueRange<float>.
  • Introduced plugin constants (PluginGuid, PluginName, PluginVersion) and updated version usage to 1.0.1.
  • Added DebugLogging config to gate high-frequency per-target logs.

• Runtime performance refactor

  • Replaced full-scene FindObjectsOfType<GameObject>() scans with non-alloc physics overlap queries (Physics2D.OverlapCircleNonAlloc, Physics.OverlapSphereNonAlloc).
  • Added lazy local-player caching with scene-change invalidation/refresh.
  • Removed string-allocation heuristics (ToLower) in favor of IndexOf(..., StringComparison.OrdinalIgnoreCase).

• Physics correctness + safety

  • Moved trigger execution from Update to FixedUpdate through a pending-action queue.
  • Removed transform-position fallback for objects without rigidbodies (skip non-physics targets).
  • Computed 2D knockback direction explicitly on planar axes before impulse application.

• Harmony behavior cleanup

  • Removed implicit Harmony PatchAll() initialization because no explicit patch classes exist in the plugin source.

• Packaged docs/metadata alignment

  • Updated packaged manifest/changelog/readme (inside zip) and root README.md to reflect new behavior/settings and version alignment.

KnockbackForce = Config.Bind(
    "Knockback", "Force", 15f,
    new ConfigDescription("Force of the knockback (higher = stronger push)",
        new AcceptableValueRange<float>(0f, 100f)));

private void Update()
{
    if (EnableMod.Value && Input.GetKeyDown(KnockbackKey.Value))
        _pendingKnockback = true;
}

private void FixedUpdate()
{
    if (!EnableMod.Value || !_pendingKnockback) return;
    _pendingKnockback = false;
    ApplyKnockbackFromLocalPlayer();
}