feat(cli): wire invoke and account commands to native flows

[peterexcel494-oss]

Summary

Closes #34

Wires up the two remaining CLI stubs identified in issue #34 so they call into native Stellar/Soroban tooling instead of printing "NOT yet implemented" banners.

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What changed

milestonex-cli invoke <method> [args...] — was a stub, now fully wired

• Shells out to stellar contract invoke with the correct flags.
• Resolves contract ID from (in priority order): CONTRACT_ID env var → SOROBAN_CONTRACT_ID → .milestonex_contract_id file written by make deploy-testnet.
• Resolves signing source from SOROBAN_SOURCE → STELLAR_SECRET_KEY.
• Reads SOROBAN_NETWORK (default: testnet).
• Uses serde_json to validate JSON args before passing to stellar-cli; warns if an arg looks like malformed JSON.
• Prints a rich usage block listing all canonical milestonex-campaign analytics methods (version, get_dashboard_metrics, get_campaign_report, get_platform_summary, etc.).

milestonex-cli account — upgraded deprecation + transparent delegation

• Replaced single-line deprecation warning with a prominent box-drawing banner.
• account create → transparently delegates to keypair generate-master (with banner).
• account fund <addr> <xlm> → transparently delegates to keypair fund (with banner).
• Unknown sub-commands print a clear redirect to the keypair namespace.

docs/deployment.md CLI status table

Command	Before	After
invoke <method>	⚠️ Stub	✅ Implemented — env var instructions included
account / account create / account fund	⚠️ Deprecated (warning)	⚠️ Deprecated (banner + transparent delegation)

README.md

• Removed invoke from the list of stubs.
• Updated quick-start Step 4 to show milestonex-cli invoke version and milestonex-cli invoke get_dashboard_metrics 1 directly.
• Troubleshooting section no longer lists invoke as a stub command.

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Acceptance criteria (issue #34)

• invoke works against CampaignContract::version and CampaignContract::get_dashboard_metrics (wired to stellar contract invoke which targets the canonical campaign contract).
• account create|fund aliases transparently to keypair generate-master|fund with deprecation warning.
• Updated CLI help table (docs/deployment.md + print_available_commands() in main.rs).

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Affected files

• crates/tools/src/main.rs
• docs/deployment.md
• README.md

Dependencies

Depends on the serde_json crate, which was already present in crates/tools/Cargo.toml. No new dependencies added.

Closes #34

[P3az3]

@peterexcel494-oss resolve conflicts

[peterexcel494-oss]

@P3az3 Please kindly review

[peterexcel494-oss]

@P3az3 Please kindly review

[peterexcel494-oss]

@P3az3 Please kindly review........

[P3az3]

LGTM