feat(brand): new mark, herald display name, docs palette

[danielcopper]

Prepares the rebrand so it can be reviewed as a whole. Draft on purpose — the checklist at the bottom has to be worked through first.

The mark

The right-hand half of a Steam Deck set in a disc, split along a 45° facet that runs unbroken across disc, body, screen and every control. It replaces the old banner, which was AI-generated and carried a garbled wordmark.

Positions and sizes sit on a millimetre grid mapped into drawing units by one constant, so the layout is adjusted by changing a measurement rather than nudging coordinates. scripts/logo/gen.py renders both the shipped asset and a contact sheet of the alternatives that were considered.

What changed

• Assets — assets/logo.svg is the source; logo.png and store_image.png are rendered from it. The old banner.png is removed rather than left orphaned.
• README — restructured around the mark: name, tagline, guide links, badges, then the Quick Access panel shot directly under them. The gallery previously sat below the feature list, far enough down that most readers never reached it. Both install routes collapse into details blocks.
• Badges — styled in the mark's own two blues instead of six unrelated colours. New: a RomM ≥ 4.9.0 badge, since that is the most common support question. The release badge reads package.json rather than the tag, because the tags carry the old project name.
• Docs site — off deep purple (which sat in RomM's colour family) onto the mark's palette, set as custom colours in both light and dark schemes. The mark becomes the site logo and favicon.
• Display name — herald, in the README and in plugin.json.
• Feature list — corrected against the code. Three claims were wrong, not merely vague: save sync was described as newest-wins (it is hash-based and blocks on genuine divergence), Steam Input as per-shortcut (it is global), and RetroDECK migration as though the plugin moves your install (it follows a move you made). Collections, save slots, RetroAchievements, multi-disc, region switching, core selection and the cleanup tools were missing entirely.

On the rename and existing installs

Decky keys a plugin's settings and data directories off the package name, not off plugin.json's name field. Verified on-device: decky-steamgriddb calls itself "SteamGridDB" and still lives in ~/homebrew/settings/decky-steamgriddb. Changing the display name is therefore free, and this PR does it — existing installs keep everything.

The risk attaches to the package name, which is what renaming the repository to herald would change. Without a migration, DECKY_PLUGIN_SETTINGS_DIR and DECKY_PLUGIN_RUNTIME_DIR would point at fresh, empty directories after the update. That is worse than it sounds, because it is not only settings.json — the SQLite database goes too, and it holds which Steam shortcut belongs to which ROM plus the save-sync baselines. The plugin would no longer recognise the shortcuts it created, so the next sync would add a second copy of every game, and with no baseline the next save sync would see divergence on every title and block on a conflict prompt for each one. The user would be left cleaning up a duplicated library by hand.

The fix is a one-shot copy at startup, shipped in the first release that carries the new package name: derive the old paths from the new ones rather than hardcoding them, act only when the new settings directory is empty and the old one is not, copy rather than move so a rollback still finds its data, write a marker so it cannot run twice, and log it. It has to run in _main before bootstrap() opens the database, and it is file I/O, so it belongs in an adapter rather than a service. It is temporary and gets deleted two or three releases later.

Full plan, tests and the removal step: #1547 — that issue deliberately stays open until the cleanup has happened.

This PR does not rename the package, so nothing here needs the migration yet. Repository and documentation URLs are untouched for the same reason.

Checklist

Mine:

• Flip repository and documentation URLs once the repository is renamed
• Add the one-shot settings and data migration before the package name changes (chore: migrate settings and data directories when the package name changes #1547)
• Cut the wordmark from the chosen typeface and add it under the mark
• Apply the corrected feature list

Yours:

• Send the message to the RomM Discord
• Decide whether to rename the repository now (recommended: before the Decky store listing, since the name sticks hard once it is published)
• After renaming: re-link the SonarCloud project (its key contains the old name), and decide whether release tags drop the decky-romm-sync- prefix
• Pick a typeface for the wordmark
• Refresh the repository description, topics and social preview image on GitHub
• Decide whether plugin.json's store description should be tightened the same way the feature list was
• Verify the display name change on-device: the QAM entry and Decky's plugin list should read "herald" while settings survive the update

docs: the documentation site's palette, logo and favicon are updated in this change.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud