feat(flomni): info popup for manual shift x in tomo parameters GUI

Add a per-field "?" help button, same pattern already used for the
offsets section and Fermat asymmetry. Explains that manual_shift_x is
a constant, angle-independent offset applied on top of the alignment,
only needed in special cases (e.g. when the FZP-to-sample distance is
changed after alignment).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NPZ9gzN2rt3wgiMnTKyrug

csaxs_bec/bec_widgets/widgets/tomo_params/tomo_params.py

@@ -528,7 +528,9 @@ class OMNY_TomoParams(BECWidget, QWidget):
                 common_form, "ptycho_reconstruct_foldername", "Reconstruct folder"
             ),
             "manual_shift": lambda: self._build_double_group(
-                common_form, self._profile["manual_shift_fields"]
+                common_form,
+                self._profile["manual_shift_fields"],
+                help_texts=self._profile.get("manual_shift_help"),
             ),
             "piezo_range": lambda: self._build_double_group(
                 common_form, self._profile["piezo_range_fields"]
@@ -572,10 +574,16 @@ class OMNY_TomoParams(BECWidget, QWidget):
         return box
 
     def _build_double_group(
-        self, form: QFormLayout, fields: list[tuple[str, str, float, float, int]]
+        self,
+        form: QFormLayout,
+        fields: list[tuple[str, str, float, float, int]],
+        help_texts: dict[str, str] | None = None,
     ) -> None:
         for key, label, min_, max_, decimals in fields:
-            self._add_double(form, key, label, min_=min_, max_=max_, decimals=decimals)
+            help_text = help_texts.get(key) if help_texts else None
+            self._add_double(
+                form, key, label, min_=min_, max_=max_, decimals=decimals, help_text=help_text
+            )
 
     def _build_int_group(self, form: QFormLayout, fields: list[tuple[str, str, int, int]]) -> None:
         for key, label, min_, max_ in fields:
@@ -626,7 +634,9 @@ class OMNY_TomoParams(BECWidget, QWidget):
         form.addRow(header_row)
         for key, label, min_, max_, decimals, _axis in self._profile["offset_fields"]:
             self._add_double(form, key, label, min_=min_, max_=max_, decimals=decimals)
-        self._build_double_group(form, self._profile["manual_shift_fields"])
+        self._build_double_group(
+            form, self._profile["manual_shift_fields"], help_texts=self._profile.get("manual_shift_help")
+        )
 
     def _show_offsets_help(self) -> None:
         QMessageBox.information(
@@ -857,14 +867,36 @@ class OMNY_TomoParams(BECWidget, QWidget):
     # ── widget factory helpers ────────────────────────────────────────────────
 
     def _add_double(
-        self, form: QFormLayout, key: str, label: str, min_: float, max_: float, decimals: int
+        self,
+        form: QFormLayout,
+        key: str,
+        label: str,
+        min_: float,
+        max_: float,
+        decimals: int,
+        help_text: str | None = None,
     ) -> QDoubleSpinBox:
         w = QDoubleSpinBox()
         w.setDecimals(decimals)
         w.setRange(min_, max_)
         w.setEnabled(False)
         self._pw[key] = w
-        form.addRow(f"{label}:", w)
+        if help_text is None:
+            form.addRow(f"{label}:", w)
+        else:
+            # same "?" help-button pattern as _build_offsets_section/
+            # _build_fermat_asymmetry_row -- a per-field popup instead of a
+            # per-group one.
+            row = QHBoxLayout()
+            row.addWidget(w, stretch=1)
+            btn_help = QPushButton("?")
+            btn_help.setFixedWidth(24)
+            btn_help.setToolTip(f"What does {label} do?")
+            btn_help.clicked.connect(
+                lambda: QMessageBox.information(self, label, help_text)
+            )
+            row.addWidget(btn_help)
+            form.addRow(f"{label}:", row)
         return w
 
     def _add_int(self, form: QFormLayout, key: str, label: str, min_: int, max_: int) -> QSpinBox:
@@ -2481,6 +2513,13 @@ SETUP_PROFILES: dict[str, dict[str, Any]] = {
             ("manual_shift_x", "Manual shift x (µm)", -10.0, 10.0, 3),
             ("manual_shift_y", "Manual shift y (µm)", -50.0, 50.0, 3),
         ],
+        "manual_shift_help": {
+            "manual_shift_x": (
+                "A constant offset applied on top of the alignment, independent of "
+                "the rotation angle. Normally zero -- only needed in special cases, "
+                "e.g. when the FZP-to-sample distance is changed after alignment."
+            )
+        },
         "piezo_range_fields": [],
         "offset_fields": [],
         "offset_getter": None,