fix(equation): 删去公式中手动 \! 负间距

\arcsin\!\big(、\Re\!\left\{、\mathbf a_\ell\!\big( 等"函数/算子+定界符"
处的手动负间距由 LaTeX 自动排版处理，无需手动加 \!。全文删 39 处。
主文件 \newcommand{\diff}{\mathop{}\!\mathrm{d}} 中的 \! 是微分号标准间距，保留。

parts/E-multiSatStaticCrb.tex

@@ -134,7 +134,7 @@ $\zeta_\ell\in\mathbb C$ 为第 $\ell$ 条链路的未知复干扰系数，$\sig
 \begin{equation}
   [\mathcal I(\boldsymbol\kappa_{\mathrm{stat}})]_{ij}
   =
-  2\Re\!\left\{
+  2\Re\left\{
     \frac{\partial \boldsymbol\mu^{\Herm}(\boldsymbol\kappa_{\mathrm{stat}})}{\partial \kappa_i}
     \mathbf R_n^{-1}
     \frac{\partial \boldsymbol\mu(\boldsymbol\kappa_{\mathrm{stat}})}{\partial \kappa_j}
@@ -237,11 +237,11 @@ $\partial\nu_{\ell_{\mathrm{ref}}}/\partial\beta=0$。若改用别的等价参
 \begin{equation}
   \alpha_\ell^{\mathrm{loc}}
   =
-  \operatorname{atan2}\!\big(u_{\ell,2}^{\mathrm{loc}},u_{\ell,1}^{\mathrm{loc}}\big),
+  \operatorname{atan2}\big(u_{\ell,2}^{\mathrm{loc}},u_{\ell,1}^{\mathrm{loc}}\big),
   \qquad
   \beta_\ell^{\mathrm{loc}}
   =
-  \arcsin\!\big(u_{\ell,3}^{\mathrm{loc}}\big).
+  \arcsin\big(u_{\ell,3}^{\mathrm{loc}}\big).
 \end{equation}
 
 对任意 $x\in\{\alpha,\beta\}$，有
@@ -439,7 +439,7 @@ $\mathbf g_\ell=\mathbf q_\ell\otimes \mathbf a_\ell$
   =
   \sum_{\ell=0}^{L-1}
   \frac{2}{\sigma_{n,\ell}^2}
-  \Re\!\left\{
+  \Re\left\{
     \mathbf J_{\eta,\ell}^{\Herm}\mathbf J_{\eta,\ell}
   \right\},
   \label{eq:A6_Itt}
@@ -448,9 +448,9 @@ $\mathbf g_\ell=\mathbf q_\ell\otimes \mathbf a_\ell$
   \mathcal I_{\eta\psi}
   =
   \begin{bmatrix}
-    \dfrac{2}{\sigma_{n,0}^2}\Re\!\left\{\mathbf J_{\eta,0}^{\Herm}\mathbf J_{\psi,0}\right\}
+    \dfrac{2}{\sigma_{n,0}^2}\Re\left\{\mathbf J_{\eta,0}^{\Herm}\mathbf J_{\psi,0}\right\}
     & \cdots &
-    \dfrac{2}{\sigma_{n,L-1}^2}\Re\!\left\{\mathbf J_{\eta,L-1}^{\Herm}\mathbf J_{\psi,L-1}\right\}
+    \dfrac{2}{\sigma_{n,L-1}^2}\Re\left\{\mathbf J_{\eta,L-1}^{\Herm}\mathbf J_{\psi,L-1}\right\}
   \end{bmatrix},
   \label{eq:A6_Itb}
 \end{equation}
@@ -459,9 +459,9 @@ $\mathbf g_\ell=\mathbf q_\ell\otimes \mathbf a_\ell$
   =
   \operatorname{blkdiag}
   \left(
-    \frac{2}{\sigma_{n,0}^2}\Re\!\left\{\mathbf J_{\psi,0}^{\Herm}\mathbf J_{\psi,0}\right\},
+    \frac{2}{\sigma_{n,0}^2}\Re\left\{\mathbf J_{\psi,0}^{\Herm}\mathbf J_{\psi,0}\right\},
     \ldots,
-    \frac{2}{\sigma_{n,L-1}^2}\Re\!\left\{\mathbf J_{\psi,L-1}^{\Herm}\mathbf J_{\psi,L-1}\right\}
+    \frac{2}{\sigma_{n,L-1}^2}\Re\left\{\mathbf J_{\psi,L-1}^{\Herm}\mathbf J_{\psi,L-1}\right\}
   \right).
   \label{eq:A6_Ibb}
 \end{equation}
@@ -502,7 +502,7 @@ $\begin{bmatrix}\mathbf g_\ell & j\mathbf g_\ell\end{bmatrix}$。虽然这两个
   =
   2\sum_{\ell=0}^{L-1}
   \frac{1}{\sigma_{n,\ell}^2}
-  \Re\!\left\{
+  \Re\left\{
     \mathbf J_{\eta,\ell}^{\Herm}
     \mathcal P_{\mathbf g_\ell}^{\perp}
     \mathbf J_{\eta,\ell}
@@ -517,7 +517,7 @@ $\begin{bmatrix}\mathbf g_\ell & j\mathbf g_\ell\end{bmatrix}$。虽然这两个
   =
   2\sum_{\ell=0}^{L-1}
   \frac{|\zeta_\ell|^2}{\sigma_{n,\ell}^2}
-  \Re\!\left\{
+  \Re\left\{
     \mathbf D_\ell^{\Herm}
     \mathcal P_{\mathbf g_\ell}^{\perp}
     \mathbf D_\ell
@@ -596,7 +596,7 @@ $\begin{bmatrix}\mathbf g_\ell & j\mathbf g_\ell\end{bmatrix}$。虽然这两个
     \frac{2}{\sigma^2}
     \sum_{\ell=0}^{L-1}
     |\zeta_\ell|^2
-    \Re\!\left\{
+    \Re\left\{
       \mathbf D_\ell^{\Herm}\mathcal P_{\mathbf g_\ell}^{\perp}\mathbf D_\ell
     \right\}.
   \end{equation}
@@ -707,7 +707,7 @@ $\mathbf J_{\psi,\ell}$ 的实参数化二维实子空间与复矩阵 $\mathbf G
   =
   \sum_{\ell=0}^{L-1}
   \frac{2}{\sigma_{n,\ell}^2}
-  \Re\!\big\{\mathbf J_{\eta,\ell}^\Herm\mathbf J_{\eta,\ell}\big\}.
+  \Re\big\{\mathbf J_{\eta,\ell}^\Herm\mathbf J_{\eta,\ell}\big\}.
 \end{equation}
 %
 由于 $\mathbf J_{\psi,\ell}$ 的实子空间等价于 $\mathbf G_\ell$ 的复列空间，关于复增益块的 Schur 补化为对 $\mathbf G_\ell$ 列空间正交补的投影。定义
@@ -730,7 +730,7 @@ $\mathbf J_{\psi,\ell}$ 的实参数化二维实子空间与复矩阵 $\mathbf G
   =
   2\sum_{\ell=0}^{L-1}
   \frac{1}{\sigma_{n,\ell}^2}
-  \Re\!\big\{
+  \Re\big\{
     \mathbf J_{\eta,\ell}^\Herm
     \mathcal P_{\mathbf G_\ell}^\perp
     \mathbf J_{\eta,\ell}
@@ -745,7 +745,7 @@ $\mathbf J_{\psi,\ell}$ 的实参数化二维实子空间与复矩阵 $\mathbf G
   =
   2\sum_{\ell=0}^{L-1}
   \frac{1}{\sigma_{n,\ell}^2}
-  \Re\!\Big\{
+  \Re\Big\{
     \zeta_{\ell,k}^*\zeta_{\ell,k'}\,
     \mathbf D_{\ell,k}^\Herm
     \mathcal P_{\mathbf G_\ell}^\perp