feat: retry starting a run on memory and concurrent-runs limits

[vdusek]

Adds a wait_for_resources argument to ActorClient.start/call and TaskClient.start/call, sync and async. When set, a start that the API rejects with actor-memory-limit-exceeded or concurrent-runs-limit-exceeded is retried every 10 seconds. Orchestrators no longer need their own wait-and-retry loop.

• True retries until the run starts. A timedelta limits the retrying, after which the last 402 error is raised.
• Any other error is raised right away.
• In call, the retry time doesn't count toward wait_duration.
• A file-like input is read into memory before the first attempt, so every retry sends it whole.
• A run that asks for more memory than the account's whole memory limit gets the same actor-memory-limit-exceeded error and never starts, so True retries it forever. The API has no separate error type for that case. The docs call it out.

The Retries concept page gets a section with sync and async examples. The JS twin is apify/apify-client-js#1091 and uses the same design.

Closes #1071

✍️ Drafted by Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.35%. Comparing base (ae17148) to head (2ded90e).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1081      +/-   ##
==========================================
+ Coverage   87.75%   95.35%   +7.59%     
==========================================
  Files          60       61       +1     
  Lines        5757     5808      +51     
==========================================
+ Hits         5052     5538     +486     
+ Misses        705      270     -435     

Flag	Coverage Δ
integration	91.15% <56.36%> (?)
unit	88.13% <100.00%> (+0.38%)	⬆️

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[Mantisus]

Could you rebase onto master to make sure this works correctly with the request body streaming added in #1060?

[Mantisus]

LGTM

[apify-approval-mirror]

Mirroring approval from @Mantisus.