port: three live-but-undocumented flags, and a dead instruction I wrote while fixing them

Their newest class -- the instruction is dead AND the working one is undocumented
-- inverts last iteration's sweep. I checked documented->parsed; the reverse is
parsed->documented, and it enumerates, so it completes rather than samples.

Eighteen flags parsed, fifteen documented, three live and undocumented:
--film-interval and --skip-at (used by verify-dwell, in no usage example) and
--no-hold, which plays a screen past its rest instead of clamping each element at
its hold, documented in DECISIONS.md and absent from the header a reader consults.
A capability that exists only in an 11000-line record does not exist to anyone
reading the interface.

Then I documented it wrong in the same command. I wrote the example as
--screen=title --no-hold --time=6 and tested it: the renders are byte-identical
because --time sets frozen and pose_at tests 'holding and not frozen', so an
explicit instant makes --no-hold inert. Without --time the pair differs by max
253. I wrote a dead instruction inside the commit fixing dead instructions, and it
only failed to ship because I ran the example rather than trusting that a parsed
flag works -- the gap I had named one iteration earlier.

Strongest evidence yet for their ranking: a wrong description costs a reader's
belief, a wrong instruction hands them a null result that looks like a finding.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N7FiFFFwbvG2uxdcEh8HyF

port/scripts/boot.gd

@@ -7,6 +7,24 @@
 #   godot --path port -- --screen=main_menu
 #   godot --path port -- --screen=main_menu --capture=/tmp/godot.png
 #   godot --path port -- --screen=main_menu --time=0.5 --capture=/tmp/at-half.png
+#   godot --path port -- --screen=title --no-hold
+#                                    # play PAST the rest instead of clamping
+#                                    # each element at its own hold.
+#                                    # ⚠️ NOT with `--time`: that sets `frozen`,
+#                                    # and `pose_at` tests `holding and not
+#                                    # frozen`, so an explicit instant makes
+#                                    # `--no-hold` a no-op. Verified: identical
+#                                    # renders with `--time`, max 253 different
+#                                    # without it.
+#   godot --path port -- --boot --film=/tmp/b --film-interval=0.1
+#                                    # frame cadence for --film (default 0.25)
+#   godot --path port -- --boot --skip-at=1  # press (A) at 1 s to skip a movie
+#
+# 🔴 THESE THREE WERE LIVE AND UNDOCUMENTED. `--no-hold` is documented in
+# DECISIONS.md and was absent from the block a reader actually consults;
+# `--film-interval` and `--skip-at` are used by `tools/port/verify-dwell` and
+# appeared nowhere else. A capability that exists only in the record is, to
+# anyone reading the interface, a capability that does not exist.
 #   godot --path port -- --screen=main_menu --pose=rest --capture=/tmp/rest.png
 #   godot --path port -- --screen=title --overlay=press_start --time=4
 #   godot --path port -- --boot                      # the whole boot sequence