feat: make pipeline9 the default autorouter

[seveibar]

Summary

• make Pipeline9 the default local autorouter and map latest to it
• preserve beta_pipeline7 as the explicit legacy Pipeline7 escape hatch
• de-duplicate unchanged preloaded traces and shared boundary vias returned across phased/fanout routing stages
• rely on the upstream Pipeline9 via-preservation fix instead of repairing autorouter output in Core
• refresh affected PCB and autorouting snapshots

Dependency

Includes the merged fix from tscircuit/tscircuit-autorouter#2204 via published @tscircuit/capacity-autorouter@0.0.836.

Validation

• published @tscircuit/capacity-autorouter@0.0.836: both targeted Core breakout tests pass with unchanged snapshots, including the no-layer-change-without-via assertion
• upstream: bun run build, bunx tsc --noEmit, and all 48 non-visual Pipeline9 feature tests
• earlier full Core suite for the Pipeline9-default change: 1,427 pass, 40 skip
• Core formatting check on touched TypeScript files
• git diff --check

Props compatibility

@tscircuit/props v0.0.628 already includes beta_pipeline7 in AutorouterVersion, its Zod schema, and its autorouter tests, so no props PR is needed.

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Project	Deployment	Actions	Updated (UTC)
tscircuit-core-benchmarks	Ready	Preview	Aug 23, 2026 3:31am

[seveibar]

Update after validating the merged autorouter release:

• @tscircuit/capacity-autorouter 0.0.836 fixes the original unrelated-winding breakout regression.
• The full Core suite exposed a second missing-via route in the A03 dependency (repro116 Arduino center reroute).
• Root fix: Fix A03 terminal layer transition trimming high-density-a01#89.
• Autorouter dependency bump: Update A03 to preserve terminal layer transitions tscircuit-autorouter#2206.
• With both fixes linked and the autorouter rebuilt, the center reroute passes: 1 test, 124 assertions, with no Core workaround.

This Core PR should wait for those stacked fixes to merge and release before its final dependency/snapshot refresh.