refactor: unify league update/summary entry points and fix params cross-refs (#42)

[pbulsink]

Summary

As a user of HockeyModel, in order to keep the public API small and consistent, I would like a single, league-agnostic entry point for updating and summarising both the NHL and PWHL, rather than separate league-specific exports that shadow the generic names.

This PR makes updateModel() and dailySummary() the single public entry points for both leagues. The former league-specific exports (updateDC(), updatePWHLDC(), updatePWHLModel(), dailyPWHLSummary()) are now internal, and the params argument across the NHL prediction/simulation/social-media functions now points at the correct source of the params list.

Behavior

1. League-specific exports demoted to internal

Before: Four public functions duplicated the behaviour of the generic updateModel() / dailySummary() while leaking league-specific names into the API:

Public export	Role
updateDC()	Fit NHL Dixon-Coles params
updatePWHLDC()	Fit PWHL Dixon-Coles params
updatePWHLModel()	Update PWHL schedule + scores + params
dailyPWHLSummary()	PWHL daily summary / social post

After: updateModel() and dailySummary() are the only public entry points. The league-specific functions are renamed to internal helpers and no longer exported:

Internal helper	Replaces
.update_dc_nhl()	updateDC()
.update_dc_pwhl()	updatePWHLDC()
.update_model_pwhl()	updatePWHLModel()
.daily_summary_pwhl()	dailyPWHLSummary()

NAMESPACE drops the four exports; devtools::document() removes the four exported .Rd pages and generates internal ones (dot-*.Rd) marked @keywords internal.

2. params cross-references fixed

Before: ~40 exported NHL functions documented their params argument with See [updateDC] — a link to a function that no longer exists once #42 is applied, and which is PWHL-agnostic in name but NHL-specific in reality.

After: Those links point at updateModel(), the function that actually produces the NHL params list. The PWHL data-object docs (pwhl_m, pwhl_rho, pwhl_beta, pwhl_eta, pwhl_k) link to .update_dc_pwhl(), their real populator.

Tests

Updated every test that referenced the renamed functions to mock/call the internal names:

• test-frontend-core.R — updateModel() dispatch tests now mock .update_model_pwhl().
• test-frontend-daily-summary.R / test-frontend-plots.R — mocks now use .daily_summary_pwhl().
• test-pwhl-daily-summary.R — test descriptions and the called function renamed to .daily_summary_pwhl().
• test-pwhl-model-core.R — updatePWHLDC / updatePWHLModel test blocks renamed to .update_dc_pwhl / .update_model_pwhl; mock of updatePWHLDC now mocks .update_dc_pwhl.
• test-nhl-dixon-coles-workflow.R / test-nhl-dixon-coles-predict.R — updateDC(...) calls renamed to .update_dc_nhl(...).
• helper-pwhl.R — comment updated.

Full suite: 803 pass, 0 fail, 0 warn, 0 skip.

Notes

• devtools::check(error_on = "warning"): 0 errors, 0 warnings, 1 NOTE. The NOTE (no visible binding for global variable 'i' in loopless_sim / simulateSeasonParallel) is pre-existing on master (introduced by the function(i) closure in PR perf: optimize season simulation loops (#45, #49, #51) #57) and unrelated to this change — this PR only touches a doc cross-reference in nhl-league-simulation.R, no code touching i.
• The 5 previously-untracked internal .Rd files (dcPredictVectorized.Rd, dcProbArray.Rd, sim_batch.Rd, sim_odds_results.Rd, simulation_chunks.Rd) are now committed; they were generated by devtools::document() in prior PRs but never staged, and are required for Rd cross-references ... OK.
• NEWS.md updated with a single user-facing bullet under the dev heading.
• No new public API; the package surface strictly shrinks by 4 exports.

References

• Closes API Cleanup #42