rofl-scheduler: Per-offer allowed_creators and allowed_artifacts

[anzoman]

Adds per-offer overrides for allowed_creators and allowed_artifacts, making it possible to mix public and internal workloads on the same scheduler instance without repeating the global allowlist for every offer.

What changed

• offers is now a BTreeMap<String, OfferConfig> internally. Each entry carries optional allowed_creators and allowed_artifacts overrides; when absent, the top-level value is used as a fallback. Empty list = allow all.
• offer_key_by_id is built once per scheduling round in discover() and reused in process_pending(), avoiding a redundant on-chain fetch.
• Fully backwards compatible — the existing plain-string array format is still accepted. New entries can optionally carry per-offer config using a map with an id field.

Config

# Global fallback — applies to all offers that don't override it
allowed_creators: []

offers:
  - playground_short            # plain string — global defaults apply
  - playground_short_sgx
  - id: oasis_internal          # map entry — per-offer overrides
    allowed_creators:
      - "oasis1abc..."

[netlify]

✅ Deploy Preview for oasisprotocol-oasis-sdk canceled.

Name	Link
🔨 Latest commit	2a5dd44
🔍 Latest deploy log	https://app.netlify.com/projects/oasisprotocol-oasis-sdk/deploys/6a1d6181d9667c00082fe58e

[codecov]

Codecov Report

❌ Patch coverage is 22.72727% with 85 lines in your changes missing coverage. Please review.
✅ Project coverage is 51.24%. Comparing base (1ca9917) to head (2a5dd44).

Files with missing lines	Patch %	Lines
rofl-scheduler/src/config.rs	34.24%	48 Missing ⚠️
rofl-scheduler/src/manager.rs	0.00%	37 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2465      +/-   ##
==========================================
- Coverage   51.33%   51.24%   -0.10%     
==========================================
  Files         237      237              
  Lines       17132    17212      +80     
==========================================
+ Hits         8795     8820      +25     
- Misses       8277     8332      +55     
  Partials       60       60              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[kostko]

Looks good, have you tested it anywhere?