docs/add file-loaded at_each_angle hook example (exposure + step size)

Adds a worked example to both lamni.md and flomni.md showing a hook
loaded from a file that temporarily bumps tomo_countingtime and
tomo_shellstep every 5th projection within sub-tomogram 2 (tomo_type 1),
restoring both in a finally block -- demonstrating that a hook can
change any scan parameter, not just move devices like the existing
polarizer example. Notes that progress["subtomo"]/["subtomo_projection"]
work the same way for tomo_types 2/3, just with an open-ended
sub-tomogram count there instead of type 1's fixed 8.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docs/user/ptychography/flomni.md

@@ -532,6 +532,47 @@ namespace, same as a cell). **Avoid plain `%run myhooks.py`** (without `-i`): it
 executes in a fresh, throwaway namespace each time, so an edit-and-rerun is *not*
 picked up automatically and the old version keeps running silently.
 
+**Example — hook loaded from a file, changing exposure and step size for a subset of
+projections:** a hook can also read `flomni.progress` and temporarily change any scan
+parameter (e.g. `tomo_countingtime`, `tomo_shellstep`) just for specific projections,
+then restore it. This example (tomo_type 1) takes a longer exposure at a finer
+real-space step every 5th projection within sub-tomogram 2, and a normal projection
+everywhere else. `~/hooks/my_hooks.py`:
+```python
+def high_res_every_5th(flomni, angle):
+    if flomni.progress["subtomo"] == 2 and flomni.progress["subtomo_projection"] % 5 == 0:
+        orig_countingtime = flomni.tomo_countingtime
+        orig_shellstep = flomni.tomo_shellstep
+        flomni.tomo_countingtime = 0.5   # longer exposure
+        flomni.tomo_shellstep = 0.2      # finer real-space step
+        try:
+            flomni.tomo_scan_projection(angle)
+        finally:
+            # restore even if the scan above raises, so a retry or the next
+            # projection doesn't silently keep running with these settings
+            flomni.tomo_countingtime = orig_countingtime
+            flomni.tomo_shellstep = orig_shellstep
+    else:
+        flomni.tomo_scan_projection(angle)
+```
+Load and use it:
+```python
+import my_hooks
+flomni.register_at_each_angle_hook("high_res_every_5th", my_hooks.high_res_every_5th)
+
+flomni.tomo_parameters()                              # set up the scan parameters as usual
+flomni.at_each_angle_hook = "high_res_every_5th"       # activate the hook
+flomni.tomo_queue_add("subtomo 2 high-res every 5th")
+
+flomni.at_each_angle_hook = None                       # reset the session default for whatever's queued next
+flomni.tomo_queue_execute()
+```
+`progress["subtomo"]`/`progress["subtomo_projection"]` are populated the same way for
+tomo_types 2/3, so the same pattern works there too — just note that unlike type 1's
+fixed 8 sub-tomograms, those types have no fixed sub-tomogram count (see
+[Tomography](user.ptychography.flomni.tomography) above), so "sub-tomogram 2" means
+something different (and open-ended) for them.
+
 **`tomo_scan_projection()` vs `tomo_acquire_at_angle()`:** these are not
 interchangeable. `tomo_scan_projection(angle)` always runs a full Fermat-scan
 projection; `tomo_acquire_at_angle(angle)` always runs a single-point acquisition.

docs/user/ptychography/lamni.md

@@ -299,6 +299,47 @@ namespace, same as a cell). **Avoid plain `%run myhooks.py`** (without `-i`): it
 executes in a fresh, throwaway namespace each time, so an edit-and-rerun is *not*
 picked up automatically and the old version keeps running silently.
 
+**Example — hook loaded from a file, changing exposure and step size for a subset of
+projections:** a hook can also read `lamni.progress` and temporarily change any scan
+parameter (e.g. `tomo_countingtime`, `tomo_shellstep`) just for specific projections,
+then restore it. This example (tomo_type 1) takes a longer exposure at a finer
+real-space step every 5th projection within sub-tomogram 2, and a normal projection
+everywhere else. `~/hooks/my_hooks.py`:
+```python
+def high_res_every_5th(lamni, angle):
+    if lamni.progress["subtomo"] == 2 and lamni.progress["subtomo_projection"] % 5 == 0:
+        orig_countingtime = lamni.tomo_countingtime
+        orig_shellstep = lamni.tomo_shellstep
+        lamni.tomo_countingtime = 0.5   # longer exposure
+        lamni.tomo_shellstep = 0.2      # finer real-space step
+        try:
+            lamni.tomo_scan_projection(angle)
+        finally:
+            # restore even if the scan above raises, so a retry or the next
+            # projection doesn't silently keep running with these settings
+            lamni.tomo_countingtime = orig_countingtime
+            lamni.tomo_shellstep = orig_shellstep
+    else:
+        lamni.tomo_scan_projection(angle)
+```
+Load and use it:
+```python
+import my_hooks
+lamni.register_at_each_angle_hook("high_res_every_5th", my_hooks.high_res_every_5th)
+
+lamni.tomo_parameters()                              # set up the scan parameters as usual
+lamni.at_each_angle_hook = "high_res_every_5th"       # activate the hook
+lamni.tomo_queue_add("subtomo 2 high-res every 5th")
+
+lamni.at_each_angle_hook = None                       # reset the session default for whatever's queued next
+lamni.tomo_queue_execute()
+```
+`progress["subtomo"]`/`progress["subtomo_projection"]` are populated the same way for
+tomo_types 2/3, so the same pattern works there too — just note that unlike type 1's
+fixed 8 sub-tomograms, those types have no fixed sub-tomogram count (see
+[Laminography scan](user.ptychography.lamni.laminography) above), so "sub-tomogram 2"
+means something different (and open-ended) for them.
+
 **GUI:** the tomo parameters panel has an "At-each-angle hook" dropdown, listing
 whatever is currently registered from the CLI (`register_at_each_angle_hook()`) —
 the GUI process can't register hooks itself, only select one by name for the job