Make derivable reduction parameters exact

[isPANN]

Several reductions marked target parameters unavailable even though their constructed values have exact formulas in registered source parameters. This PR adds 24 such formulas across 22 rules. For example, ExactCoverBy3Sets → ILP now reports num_nonzeros = 4 * num_subsets. HamiltonianPath → ILP reports all three ILP sizes exactly, including the empty-graph case, using a source parameter for consecutive positions. BMF → BicliqueCover no longer claims an exact edge count from matrix dimensions alone.

One registry-wide test checks every declared formula field against a constructed target: equality for exact, and predicted ≥ measured for upper_bound. It uses canonical examples or registered generators where examples are unavailable. Turing Decision wrappers and two proof-only rules have test-only target constructions because they have no single-shot reduction callback. This check caught a false QUBO → SpinGlass exact claim: sparse QUBOs do not have num_vars² interactions. QUBO now exposes its natural nonzero quadratic-term count, which restores an exact interaction formula and also makes all three QUBO → ILP size formulas exact. The canonical instructions and add-rule guide now require coverage for every formula field in future rules.

Validation: make check passed (formatting, Clippy, workspace tests, and doctests).

[codecov]

Codecov Report

❌ Patch coverage is 96.25668% with 14 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.74%. Comparing base (309ac65) to head (84f1bd2).

Files with missing lines	Patch %	Lines
src/unit_tests/parameter_formula_validation.rs	90.90%	14 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1174      +/-   ##
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+ Coverage   96.73%   96.74%   +0.01%     
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  Files        1069     1070       +1     
  Lines      138549   138920     +371     
==========================================
+ Hits       134023   134397     +374     
+ Misses       4526     4523       -3     

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