fix(7-segment-clock): draw the digits at all, and document every setting

[ChuckBuilds]

Summary

First plugin in a pass to bring every ChuckBuilds-owned plugin README up to a
consistent standard: real rendered screenshots, and a documented explanation of
every configuration option.

While generating the screenshots for this one I found the plugin doesn't draw
anything at all.

The rendering bug

The digit assets in assets/images/ are 1-bit bitmaps with no alpha channel,
but _render_digit only lit pixels whose alpha was 0 — a condition those
assets never satisfy. Every segment was skipped, so the plugin rendered a black
panel at every size. Neither failure path raises, so it presented as "the clock
doesn't show up" rather than an error.

Evidence it was a live regression rather than intended behaviour:

• plugins/7-segment-clock/test_render_polarity.py was failing on main
• the committed golden images drift on all eight harness sizes on main:

[FAIL]   64x32  golden drift: 698px (max Δ=255)
[FAIL]  128x32  golden drift: 698px (max Δ=255)
[FAIL]   64x64  golden drift: 522px (max Δ=255)
[FAIL]   96x48  golden drift: 1532px (max Δ=255)
[FAIL]  128x64  golden drift: 2733px (max Δ=255)
[FAIL]  256x32  golden drift: 698px (max Δ=255)
[FAIL]  128x96  golden drift: 3544px (max Δ=255)
[FAIL] 256x128  golden drift: 7062px (max Δ=255)

After the fix all eight pass against those same unmodified goldens.

Lit segments now come from the bright pixels, and the digit and separator paths
share one _colorize helper instead of two copies of the same pixel loop. The
polarity test's docstring described the wrong polarity, which is presumably how
the regression got written; that's corrected too.

The stale-clock bug

display() used the current_time cached by update(), but the scheduler only
calls update() once per manifest update_interval — 60s here. So the panel
could show a time up to a minute stale, and has_flashing_separator never
actually flashed: the separator state is derived from the seconds field of that
frozen timestamp, so it held one state for the whole minute and then jumped.

display() now re-reads the clock each tick. clock-simple already does this;
reading the system clock is not I/O, so it belongs in display().

README

Rewritten around real plugin output — a hero shot plus a comparison grid per
setting. Every config key gets its own section with accepted values and what it
looks like on a panel. Two previously undocumented behaviours are now written
down:

• the timezone resolution order (plugin config → main config → UTC)
• the auto-scaler sizes digits from digit width alone and ignores
  digit_spacing, so a large gap pushes the outer digits off a 64-wide panel —
  shown in the grid rather than just asserted

Tooling

scripts/render_docs_assets.py drives the core renderer from a declarative shot
list (docs/assets/<id>/shots.json) and assembles the labelled grids, so README
images are reproducible instead of hand-made. A freeze_time shim pins what the
plugin thinks "now" is, so re-rendering is deterministic and
--check can verify the committed images still match the plugin.

Images live in docs/assets/ rather than plugins/<id>/assets/ so plugin
installs stay lean.

Verification

• python scripts/check_plugin.py --plugin 7-segment-clock — 8/8 PASS, goldens match
• python test_render_polarity.py — 3/3 pass
• python scripts/check_module_collisions.py — OK across 43 plugins
• manifest bumped 1.0.3 → 1.0.4, plugins.json regenerated via update_registry.py

🤖 Generated with Claude Code

[coderabbitai]

Important

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Run ID: b8e2e103-640f-499b-b026-e7196cdf16d2

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[codacy-production]

Not up to standards ⛔

🔴 Issues 2 critical

Alerts:
⚠ 2 issues (≤ 0 issues of at least minor severity)

Results:
2 new issues

Category	Results
Security	2 critical

View in Codacy

🟢 Metrics 85 complexity

Metric	Results
Complexity	85

View in Codacy

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