v0.2.6

This release moves Tally onto the consolidated Sigil package graph and records a fresh lock against the released post-cutover dependency chain.

• Select Sigil runtime, run, args, and test packages from the 0.19 monorepo tag.
• Move MCP to 0.17.1 and pin HTTP 0.18.4 so relocks cannot resurrect the archived socket provider.
• Declare the native test harness correctly with Sigil 0.19 test and test-runner dev dependencies.
• Preserve the 0.18 runtime guard/continuation compatibility changes and estate metadata.
• Remove obsolete development redirects for packages reabsorbed into Sigil.

Verification: clean native build and all 40 Tally tests pass. The regenerated 17-entry lockfile contains no archived standalone-provider URLs.