vulkan: final cleanup of chunked GDN intra/inter shaders

Intra:
- Strip all section/inline comments to match codebase style
- Add [[unroll]] to fixed-bound loops (A-matrix zero, W/U tile init/write)
- Guard chunk_len==0 underflow on s_decay[chunk_len-1]

Inter:
- Strip final comment

No functional changes. 16/16 tests pass.

ggml/src/ggml-vulkan/vulkan-shaders/gated_delta_net_chunk_inter.comp

@@ -105,7 +105,6 @@ void main() {
         }
     }
 
-    // Write final state to dst at s_off
     [[unroll]] for (uint i = 0; i < S_V; i++) {
         final_out[s_off + state_base + col * S_V + i] = state[i];
     }

ggml/src/ggml-vulkan/vulkan-shaders/gated_delta_net_chunk_intra.comp

@@ -2,8 +2,6 @@
 
 #extension GL_EXT_control_flow_attributes : require
 
-// Intra-chunk WY decomposition for chunked gated delta net
-
 layout(constant_id = 0) const uint S_V = 128;
 layout(constant_id = 1) const uint CHUNK_SIZE = 64;
 
@@ -28,7 +26,7 @@ layout(binding = 3) readonly  buffer BetaBuf   { float beta_in[];   };
 layout(binding = 4) writeonly buffer WBuf      { float w_out[];     };
 layout(binding = 5) writeonly buffer UBuf      { float u_out[];     };
 layout(binding = 6) writeonly buffer DecayBuf  { float decay_out[]; };
-layout(binding = 7) writeonly buffer GCumBuf   { float gcum_out[];  };  // per-token g_cumsum
+layout(binding = 7) writeonly buffer GCumBuf   { float gcum_out[];  };
 
 const uint A_STRIDE = CHUNK_SIZE + 1;
 shared float s_A[CHUNK_SIZE * A_STRIDE];
@@ -54,7 +52,6 @@ void main() {
     const uint global_t = chunk_start + tid;
     const bool valid = tid < chunk_len;
 
-    // Load beta and gate
     if (valid) {
         const uint gb_off = seq_id * sb3 + global_t * sb2 + head_id * sb1;
         s_beta[tid] = beta_in[gb_off];
@@ -89,7 +86,7 @@ void main() {
         }
     }
 
-    for (uint j = 0; j < CHUNK_SIZE; j++) {
+    [[unroll]] for (uint j = 0; j < CHUNK_SIZE; j++) {
         A(tid, j) = 0.0;
     }
     barrier();
@@ -119,7 +116,6 @@ void main() {
     }
     barrier();
 
-    // Forward substitution: T = (I + A)^{-1}, in-place
     for (uint i = 1; i < chunk_len; i++) {
         if (tid < i) {
             float sum = 0.0;
@@ -136,14 +132,13 @@ void main() {
     }
     barrier();
 
-    // W and U via tiled broadcast accumulation
     const uint out_base = ((seq_id * n_chunks + chunk_id) * H + head_id) * CHUNK_SIZE * S_V;
     const uint TILE_D = 32;
 
     for (uint d_start = 0; d_start < S_V; d_start += TILE_D) {
         float my_w[TILE_D];
         float my_u[TILE_D];
-        for (uint d = 0; d < TILE_D; d++) {
+        [[unroll]] for (uint d = 0; d < TILE_D; d++) {
             my_w[d] = 0.0;
             my_u[d] = 0.0;
         }
@@ -154,7 +149,6 @@ void main() {
             const uint vj_off = seq_id * sv3 + j_global * sv2 + head_id * sv1;
             float eg = exp(s_decay[j]);
 
-            // Broadcast tile of k[j] and v[j]
             for (uint d = tid; d < S_V; d += CHUNK_SIZE) {
                 if (d >= d_start && d < d_start + TILE_D) {
                     s_k_broadcast[d] = k_in[kj_off + d] * eg;
@@ -173,17 +167,15 @@ void main() {
             barrier();
         }
 
-        // Write tile to global memory
         if (valid) {
-            for (uint d = 0; d < TILE_D; d++) {
+            [[unroll]] for (uint d = 0; d < TILE_D; d++) {
                 w_out[out_base + tid * S_V + d_start + d] = my_w[d];
                 u_out[out_base + tid * S_V + d_start + d] = my_u[d];
             }
         }
     }
 
-    // Output total chunk decay
-    if (tid == 0) {
+    if (tid == 0 && chunk_len > 0) {
         const uint decay_idx = (seq_id * n_chunks + chunk_id) * H + head_id;
         decay_out[decay_idx] = s_decay[chunk_len - 1];
     }