fix(cli): accept -l/--ledger on query/insert/upsert/update

[bplatz]

Summary

The data commands (query, insert, upsert, update) only accepted the ledger as a positional argument, so the documented form

fluree query --ledger knowledge-base:main '<SPARQL>'

errored with unexpected argument '--ledger' found. Meanwhile the metadata commands (history, branch, graph, show, drop) already used a --ledger flag — an inconsistency reported in #1368.

Changes

• Add -l/--ledger to query, insert, upsert, and update as an explicit alternative to the positional ledger argument.
• New shared resolve_inputs(ledger_flag, args) wraps the existing resolve_positional_args: when --ledger is given it takes precedence and bypasses the looks_like_query heuristic (positionals carry only inline data/query or a file path; a stray second positional is rejected with a clear usage error). When the flag is absent, positional behavior is unchanged.
• Both forms now work:

  fluree query knowledge-base:main 'SELECT …'            # positional (still works)
  fluree query --ledger knowledge-base:main 'SELECT …'   # flag (now works)

• Document the flag in the docs/cli/{query,insert,upsert,update}.md option tables.

Tests

• query_and_insert_accept_ledger_flag and query_ledger_flag_rejects_extra_positional in fluree-db-cli/tests/integration.rs.
• Full CLI integration suite passes (95); cargo fmt + clippy --all-features --all-targets -D warnings clean.

Closes #1368