Surface code 1 demo refactor followup

[eliotheinrich]

Description

This PR is a follow-up to #685, addressing the issues in #704 as well as adding a few new CLI args. These new args are purely additive, so this PR should otherwise have identical behavior on the happy paths of #685.

Cleanup

• Removed mentions of inproc_rpc from realtime_relay_bp.rst
• Restored MANUALLY_INJECT_ERRORS for quantinuum-emulate path for testing
• Cleaned up remaining stale references to p_spam, decoding_window, and use-relay-bp
• Validated geometry of loaded decoder config against requested error model

New features

• Added support for providing parameters for inner decoder of sliding window decoder
• Added support for decoder params provided at CLI

Runtime / performance impact

N/A

Self-review checklist

Please confirm each item before requesting review. Check [x] or strike
through and explain.

Before requesting review

• I reviewed my own full diff in GitHub or my editor.
• PR is in Draft if it is not yet ready for review.
• Temporary / debugging changes have been removed.
• Local test logs reviewed; no unexplained warnings or errors.
• CI logs reviewed; no unexplained warnings or errors.
• Full CI has been run.

Scope and size

• PR is under ~1000 lines, or an exception is justified in the description.
• Refactoring-only changes are isolated in their own PR(s).
• No existing tests were disabled or modified just to make this PR pass
  (if so, an issue has been raised).

Tests

• New functionality has new tests.
• Tests fail if the new functionality is broken (including crashes), not
  just when it is missing.
• Negative tests added where exceptions are expected.
• Truth data added where simple EXPECT_* / assert checks are
  insufficient for algorithmic correctness.
• CI runtime impact considered; team notified if significant.

Documentation

• Public-facing APIs have Doxygen docs.
• User-visible behavior changes have public docs, or a follow-up is
  tracked.

Code style

• Naming follows the existing convention (snake_case vs camelCase) for
  the area being modified.

Dependencies

• No new third-party dependencies, or the team has been notified and
  OSRB tickets filed.

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[eliotheinrich]

/ok to test fe130ac

[bmhowe23]

/ok to test 12edb3c

[bmhowe23]

/ok to test dc4314a