feat(contracts): implement content flagging mechanism

[Birdmannn]

Pull Request Template

Description

What was added

types.rs

• DataKey::FlagRecord(u64, Address) — tracks whether a specific user has flagged a specific content ID
• DataKey::FlagCount(u64) — running tally of total flags per content ID
• Error::AlreadyFlagged — returned when a user attempts to flag the same ID more than once

governance.rs (new)

A new GovernanceContract with three public functions:

Function	Description
flag_content(env, user, target_id)	Flags a content ID on behalf of user. Requires auth, rejects duplicates, increments count, emits ContentFlagged event.
get_flag_count(env, target_id)	Returns the total number of flags for a given ID.
has_flagged(env, user, target_id)	Returns whether a user has already flagged a given ID.

lib.rs

• Registered the governance module and re-exported GovernanceContract / GovernanceContractClient.

Anti-spam design

Each flag is keyed by (target_id, user_address) in persistent storage. A second call from the same user on the same ID returns Error::AlreadyFlagged immediately, making spam-flagging impossible at the contract level.

Tests (test.rs)

Test	Covers
test_flag_content_increments_count	Count goes from 0 → 1 after a single flag
test_flag_content_multiple_users	Two different users each increment the count
test_flag_content_duplicate_panics	Same user flagging twice panics
test_has_flagged_returns_false_before_flag	has_flagged is false before any flag
test_flag_counts_are_independent_per_id	Flagging ID 1 does not affect ID 2

All 39 tests pass.

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Checklist

• I have tested my changes locally
• I have updated documentation as needed
• I have run npx prisma generate after schema changes
• I have run npx prisma migrate dev or npx prisma migrate deploy as appropriate

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Post-Merge Steps for Maintainers

If this PR includes changes to the Prisma schema:

1. Run the following command to apply the migration to your database:

   npx prisma migrate deploy

   or, for local development:

   npx prisma migrate dev

2. Ensure your CI pipeline runs the migration before tests (add this step if missing):

   - name: Run Prisma Migrate
     run: npx prisma migrate deploy

3. Make sure the database user in CI has permission to run migrations.

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If you have any questions, please comment on this PR.
this PR closes #210

[3m1n3nc3]

Please resolve the conflicts