KP to Hand Rotations

[whuang37]

Added an additional function to convert keypoints into hand angle rotations. should enable some gesture recording and stuff into the simulator. Test file shows forward backward kinematics.

[ruofeidu]

Follow https://google.github.io/styleguide/tsguide.html#method-and-function-comments

Suggest to Adherence to Coding Guidelines :) The project rules require comments to use third-person verbs and end with periods. Some comments in this PR use imperative verbs or omit ending periods.

In HandPoseFK.ts:
Line 260: // Map joint positions $\rightarrow$ // Maps joint positions.
Line 272: // Helper to build palm basis $\rightarrow$ // Builds the palm basis.
Line 330: // Pre-build child mapping $\rightarrow$ // Pre-builds child mapping for fast lookup.
Line 338: // 2. Iterate remaining joints $\rightarrow$ // 2. Iterates remaining joints in hierarchical order.
Line 349: // Get the child $\rightarrow$ // Gets the child to define the bone direction.
Line 351: // Safety check $\rightarrow$ // Performs a safety check.
Line 384: // Save final orientation $\rightarrow$ // Saves final orientation for children propagation.

In HandPoseIK.test.ts:
// 1. Forward Kinematics to get $\rightarrow$ // 1. Runs Forward Kinematics to get joint positions/orientations.
// 2. Inverse Kinematics to get $\rightarrow$ // 2. Runs Inverse Kinematics to reconstruct rotations.
// 3. Forward Kinematics again $\rightarrow$ // 3. Runs Forward Kinematics again with reconstructed rotations.
// 4. Assert that the recomputed $\rightarrow$ // 4. Asserts that the recomputed joint positions match original positions.

[ruofeidu]

follow https://google.github.io/styleguide/tsguide.html#method-and-function-comments

[ruofeidu]

In normal scenarios, these points are non-collinear and non-coincident. However, if the keypoints are corrupted or contain degenerate values (all zeros), the cross product will be [0, 0, 0], leading to a singular basis matrix. When passed to THREE.Quaternion.setFromRotationMatrix(matrix), this can result in NaN quaternion coordinates.