fix(utils): write console progress only to an interactive stdout

ProgressTracker attached ConsoleProgressDisplay unconditionally, so any
script or CI job that piped or redirected stdout had one progress bar per
stage written into its output, escape sequences included. A plain
`python demo.py > out.txt` captured 173 bytes of progress-bar noise around
10 bytes of the program's own output.

Console progress is now attached only when stdout is an interactive
terminal, when running under Jupyter, or when SEMANTICA_FORCE_PROGRESS is
set. FileProgressDisplay is untouched, so progress logging still works in
pipelines, and SEMANTICA_DISABLE_PROGRESS keeps its existing meaning and
still takes precedence.

Both progress environment variables are now documented in the README and
the utils reference; SEMANTICA_DISABLE_PROGRESS previously existed only in
the reference page.

Deviations from the issue: the issue suggested disabling the tracker on
non-TTY stdout. This gates the display instead, because disabling the
tracker would short-circuit before FileProgressDisplay and take file
progress logging down with it, and the ~20 modules that set
`progress_tracker.enabled = True` in __init__ would need the property
setter taught about TTY state to avoid undoing it. Gating the display
leaves both alone.

Design note: the claim comment on the issue proposed an
`enabled: Optional[bool] = None` constructor opt-in; during implementation
the opt-in became SEMANTICA_FORCE_PROGRESS, which needs no signature change
and follows the NO_COLOR/FORCE_COLOR convention. Known limitation: TTY
detection runs once at tracker construction (the tracker is a process-wide
singleton), so a process that redirects stdout after first use needs the
env vars to change behaviour.

Fixes #1185

docs/reference/utils.md

@@ -77,7 +77,17 @@ Most users won't call utils directly: it's the **shared foundation** for all mod
     export SEMANTICA_LOG_LEVEL=DEBUG
     export SEMANTICA_LOG_FORMAT=json     # "json" | "text"
     export SEMANTICA_DISABLE_PROGRESS=true
+    export SEMANTICA_FORCE_PROGRESS=true
     ```
+
+    <Tip>
+      **Progress bars follow your terminal.** Console progress is written only when
+      stdout is an interactive terminal (or a Jupyter notebook), so piping or
+      redirecting output no longer fills logs with progress bars and escape
+      sequences. Set `SEMANTICA_DISABLE_PROGRESS` to silence progress even in a
+      terminal, or `SEMANTICA_FORCE_PROGRESS` to keep it when stdout is redirected.
+      `SEMANTICA_DISABLE_PROGRESS` wins if both are set.
+    </Tip>
   </Step>
 </Steps>