docs: retitle the showcase entries and add two simulation runs

[LivXue]

Summary

The showcase named the artifact type rather than the run, so a reader scanning the
section learned the format and not the work. This retitles four entries and adds two.

Retitled:

entry	before	after
game	An FPS game, picked, built and judged	An FPS boss arena game, built in Godot 4
frameworks	Six orchestration frameworks, compared	Six agent-orchestration frameworks, compared
posters	A light-pollution poster campaign	How light pollution steals wildlife sleep
explainer	An interactive explainer and its solver	Why GPS needs a fourth satellite

Added as the last two entries, closing the section:

• A beam's limit load, found by bisection. A CalculiX cantilever is driven to its
  plastic limit, and eight rounds of bisection narrow the bracket from 1800-2000 kN
  down to 3.125 kN, or 0.16 percent.
• A dam break, tuned until the water stays bounded. Seven rounds tune the solver
  until the water fraction stays inside [0,1]; the out-of-bounds excursion falls from
  1e0 to 1.36e-10 once the MULES correction is switched off.

Both new entries carry the same task graph shape: Raven-Research into Raven-Code into
Raven-Oncall, run in sequence, 3 of 3 done.

Sign-offs taken before publishing:

• Every title, English and Chinese, is the owner's own final wording.
• The dam-break title states the objective the run drives down, the water fraction
  staying inside [0,1], which is what the footage's own metric panel tracks.
• The dam-break recording was re-rendered to drop a Chinese parameter label so
  both READMEs can share it; its frames were re-read round by round to confirm.
• The two recordings render at 90 percent width and their task graphs at 100.
  Only the recordings are portrait, 720x1260 against the 2270x400 of the bars
  beside them, so only they gain height back from a narrower box.
• The comparison-board alt text still reads "six orchestration frameworks" while
  its title now reads "agent-orchestration". That is deliberate: the alt describes
  what the image shows, and the board's own wording did not change.

Assets: the four new files, two run recordings and two task graphs, are hosted on the
asset issue and referenced by URL, because the repository bans image files by
extension at any size. Each was checked byte for byte against its local source after
upload.

Type

• Fix
• Feature
• Docs
• CI / tooling
• Refactor
• Other

Verification

Scoped with three dots throughout. git diff origin/main...HEAD is two files, 38
insertions and 8 deletions, and git rev-list --left-right --count origin/main...HEAD
is 0 3 after a rebase onto the current base.

• uv run --frozen --all-extras pytest tests/test_cli_onboard_commands.py tests/test_docker_runtime.py tests/test_living_docs.py -q gave 346 passed. Those are the tests that read the root READMEs.

• make lint check-commits check-large-files check-source-language all exit 0 at the rebased head.

• Rendered both files through the GitHub markdown API. Each returns one video player, 41 images, 69 cells, zero empty cells and eleven bold titles, and the eleven come back in the same order in both languages, with the two new entries last.

• Both READMEs carry the same four new asset URLs. The only per-language assets are the three that were already language-specific before this branch.

• Grepped the whole tracked tree, with no path filter and no extension filter, for the four retired titles in both languages: zero hits outside these two files.

• Checked the added lines against every retired term in the repository's _Avoid_ entries. One term matched, run, which that entry retires as a TUI transcript construct; the same phrase, run in sequence, is already on origin/main in this exact alt-text position.

• Relevant tests pass locally

• Relevant lint / type checks pass locally

• User-facing docs or screenshots are updated when needed

Risk

Text and image references on two README files. No code path, no schema, and nothing
links to a title. The section grows by one table, so the page is longer and pulls two
more assets, the larger of which is 8.5 MB.

Rollback is a revert of the three commits.

• Security impact considered
• Backward compatibility considered
• Rollback path is clear for risky changes

Related Issues

505 hosts the four assets this adds. Nothing is closed by this PR.

[gloryfromca]

No blockers; this can merge as far as I am concerned.

I reviewed the full diff and the surrounding showcase/history. I also covered AGENTS.md/CLAUDE.md, canonical terminology via CONTEXT-MAP.md, README consumers, backward compatibility, test weakening (none), and architecture constraints (not implicated by this documentation-only change). The English and Chinese entries stay structurally aligned, the new assets are external as required, and the retired titles have no remaining consumers.

Independent verification:

• uv run --frozen --all-extras pytest tests/test_cli_onboard_commands.py tests/test_docker_runtime.py tests/test_living_docs.py -q: 346 passed.
• uv run python scripts/check_large_files.py github/main..HEAD: passed.
• uv run python scripts/check_source_language.py github/main..HEAD: passed.
• git diff --check github/main...HEAD: passed.
• GitHub Markdown rendering produced matching image and cell counts for both READMEs; all four new attachment URLs returned partial PNG/GIF content successfully.