Basic support for searching for ROFL apps by app name fragment

[csillag]

This is built on top of #1960.

Suggested test URLs:

• For multiple results: http://localhost:1234/search?q=wt3
• For a single match, which we jump into: http://localhost:1234/testnet/sapphire/search?q=ollama

Closes #1969.

[github-actions]

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[csillag]

This code has now been updated to work with the latest nexus version (v0.6.14) which is not yet deployed on the OPF server instances. When running with older Nexus versions, it will provide false matches among the results. If someone wants to test the code against the old nexus version, just drop the last commit which removes the client-side workaround.

(But this workaround won't be needed as soon as latest nexus is deployed, in a few hours.)

[csillag]

This code has now been updated to work with the latest nexus version (v0.6.14) which is not yet deployed on the OPF server instances. When running with older Nexus versions, it will provide false matches among the results. If someone wants to test the code against the old nexus version, just drop the last commit which removes the client-side workaround.

(But this workaround won't be needed as soon as latest nexus is deployed, in a few hours.)

Nexus deployed, so this is no longer relevant.

[csillag]

This has been rebased on latest master, and is now ready to be reviewed / merged