refactor: replace examples with focused rustdoc examples

[kwsantiago]

Closes #1973

Changes

• Removed /examples folder containing CLI-heavy examples
• Added focused rustdoc examples to key functions:
  • IndexedTxGraph::new() - graph initialization
  • BdkElectrumClient::new() - client creation
  • BdkElectrumClient::sync() - blockchain sync
  • BdkElectrumClient::full_scan() - wallet restoration
  • TxGraph::insert_tx() - transaction insertion
  • TxGraph::balance() - balance calculation
  • TxGraph::filter_chain_unspents() - UTXO retrieval
  • KeychainTxOutIndex::reveal_next_spk() - address generation
  • KeychainTxOutIndex::insert_descriptor() - descriptor setup
  • IndexedTxGraph::apply_block_relevant() - block processing
  • EsploraExt::full_scan() - Esplora wallet scanning
• Updated Cargo.toml workspace members

Rationale

The previous examples contained 300+ lines of CLI boilerplate that obscured the core BDK functionality. The new rustdoc examples are 10-15 lines each and focus purely on API usage, making them much easier for developers to understand and follow.

The maintained bdk-cli tool serves as the comprehensive CLI example.

[oleonardolima]

Thanks for working on this one. It's failing on CI. Make sure to use the 'just' commands and try building the docs locally if that helps with debugging the failures.

[kwsantiago]

@oleonardolima thank you. CI "should" be fixed now, at least it is locally. Can we try again?

[oleonardolima]

Thanks, there are some unrelated already merged commits, you probably need to do a rebase on top of master. Also, please note that we follow the conventional commits for commit messages, which would also need an update.

[kwsantiago]

@oleonardolima ok should be ready to test CI now. Thanks!

[oleonardolima]

You'll need to perform another rebase to incorporate the CI updates/fixes, and remove the unrelated merge commit.

[kwsantiago]

@oleonardolima should be good now, let me know if there is anything else here.

[notmandatory]

cACK, but haven't done a close review yet. Thanks for hanging in on this one, but looks like it needs another rebase.

[oleonardolima]

I'm sorry for all the rebases you had to do, but you'll need another one to get the latest CI with bumped MSRV.