Emit structured indexed events with topics for all vault lifecycle transitions

[1nonlypiece]

📌 Description

src/lib.rs publishes vault_created, milestone_validated, funds_released,
funds_redirected, and vault_cancelled, but the topic/data layout is
inconsistent — some carry the full ProductivityVault, some carry only the
amount, some carry (). Indexers consuming these (see the event-monitoring
section of src/doc.md) need a stable, predictable schema.

This issue standardizes event topics and data into a documented, indexable shape.

Goal: give every lifecycle event a consistent topic tuple and a typed data
payload, then document the schema for off-chain consumers.

🎯 Requirements and Context

• Must be tested and documented.
• Each event topic should be (event_name, vault_id, creator) so indexers can
  filter by creator without decoding data.
• Data payloads should be typed structs/tuples (amount, destination, status).
• Keep event names backward-compatible where possible; document any change.
• Verify emission via env.events() assertions, not just snapshots.

🛠️ Suggested Execution

1. Fork the repo and create a branch

git checkout -b feature/structured-events

2. Implement changes

• Contract: update every env.events().publish(...) call in src/lib.rs to the
  standardized topic/data shape.
• Tests: add tests/events.rs asserting topics and decoded data for each
  transition using env.events().all().
• Docs: rewrite the event-monitoring section of src/doc.md and add
  docs/EVENTS.md with the full schema table.
• Add NatSpec-style /// comments documenting each emitted event.

3. Test and commit

• Run cargo test.
• Cover edge cases: events for create, validate, release (validated + deadline),
  redirect, cancel; assert vault_id and creator topics on each.

Example commit message

feat: standardized indexed lifecycle events with schema docs and tests

✅ Guidelines

• Minimum 95% test coverage on new/changed event paths.
• Clear documentation of the event schema for indexers.
• No regressions on existing event names where preserved.
• Timeframe: 96 hours.

🏷️ Labels

type-enhancement · area-contracts · type-documentation ·
MAYBE REWARDED · GRANTFOX OSS · OFFICIAL CAMPAIGN

💬 Community & Support

• Join the Disciplr contributor Discord to coordinate, ask questions, and get
  unblocked fast: https://discord.gg/xvNAvMJf
• Please introduce yourself before you start so we can avoid duplicate work,
  pair you with a reviewer, and merge your PR quickly.

[dangelo352]

I can take this. I’ll keep the event names backward-compatible while standardizing topics to (event_name, vault_id, creator), add typed payloads for amount/destination/status where relevant, assert emissions with env.events(), and document the schema for indexers.

[leocagli]

I'd like to work on this issue, please assign me so I can begin implementation.

[hakymulla]

I'd like to apply for this issue. I have open source experience on the stellar ecosystem.