refactor: remove fmo_frontend and upgrade Fedimint to v0.10

[elsirion]

Summary

• Remove the Leptos-based fmo_frontend (replaced by fmo_frontend_react)
• Upgrade all Fedimint dependencies from 0.8.0-beta.2 to 0.10.0
• Switch from elsirion's fork to official fedimint repo

Changes

Frontend Removal

• Deleted entire fmo_frontend/ directory
• Removed from workspace, justfile, flake.nix, CI workflow
• Updated documentation (README.md, CLAUDE.md)

Fedimint v0.10 Upgrade

• Updated all fedimint dependencies to v0.10.0
• Added new fedimint-connectors dependency
• Updated API usage for breaking changes:
  • Connector → ConnectorRegistry
  • DynGlobalApi::from_endpoints() → DynGlobalApi::new()
  • Added download_from_invite_code for config fetching
• Added ConnectorRegistry field to FederationObserver

Build Changes

• Added cmake to nix devShell (required for aws-lc-sys)

Test plan

• cargo clippy passes
• cargo test passes
• Manual testing with running federations

🤖 Generated with Claude Code

[tacio]

I built and ran this version of fmo_server, syncing 5 federations, including old and new ones and compared the data between this version of FMO (with fedimint 0.10) to the previous version.
Everything matched, the only difference I noticed was that in the consensus_items table in kind="wallet", where the data was {"Default": {"bytes": [2, 2], "variant": 3}} it is now {"ModuleConsensusVersion": {"major": 2, "minor": 2}} which seems an upgrade, the content now has semantic information.

Everything else, sessions, transactions, transaction_inputs, transaction_outputs, transaction_input_details, transaction_output_details, and consensus_items have matched 100%, and I also looked at the guardian_health table and it seems... healthy.

(I can't evaluate the changes in the frontend though)

[tacio]

Oh, I didn't validate nostr stuff, sorry.

[tacio]

build is failing because cmake is missing from nativeBuildInputs in flake. Claude only added it to devShells.

[elsiribot]

Rehoming this from the elsirion personal repo onto elsiribot's fork so CI/babysit tooling can interact with it. Continued in a new PR (link to follow).

[elsiribot]

Superseded by #115 (rehomed onto elsiribot fork so babysit/CI tooling can push fixes). Please close this one when convenient.