skillscript-runtime v0.18.7

Closes a discoverability gap noticed during a .env audit: three
operator-controllable behaviors were programmatic-only or config-only
without a .env-natural path, so operators tuning prod or test
environments had to write code (or a JSON config) to change them.
v0.18.7 surfaces all three through the standard cascade (CLI flag >
env > config > default).

Three knobs surfaced

Knob	Env var	Was	Now
Scheduler poll interval	SKILLSCRIPT_POLL_INTERVAL_SECONDS	config + bootstrap	+ env path
Runtime absolute timeout	SKILLSCRIPT_ABSOLUTE_TIMEOUT_MS	programmatic-only (ctx.absoluteTimeoutMs)	+ config + env + bootstrap opt
Composition recursion depth ceiling	SKILLSCRIPT_MAX_RECURSION_DEPTH	programmatic-only (ctx.maxRecursionDepth); hardcoded 10	+ config + env + bootstrap opt

absoluteTimeoutMs defaults to 300_000ms (5 minutes); maxRecursionDepth
defaults to 10 (DEFAULT_MAX_RECURSION_DEPTH); poll interval defaults
to 30 seconds. All values flow through BootstrapOpts → Scheduler
config → per-dispatch ExecuteContext.

Tests

10 new tests in v0.18.7-operator-knobs.test.ts:

• Config schema accepts each new field with positive-integer validation
• Rejects 0 / negative / non-integer / non-numeric values for both
• All three knobs co-set in one config + omission preserves defaults
• Scheduler accepts the two new fields and constructs cleanly

1729 tests total; typecheck clean; LOC budget holds.

Docs

• scaffold/.env.example — new "Runtime tuning" section documenting all
  three vars with use-case framing + defaults
• docs/configuration.md — env-var precedence table extended; field
  docstrings on SkillscriptConfig interface explain cascade

Adopter migration

None — all changes are additive and backward-compatible. Adopters
relying on the old programmatic-only paths (passing ctx.absoluteTimeoutMs
directly to execute()) continue to work; the new layers just add
operator surfaces below them. Default behavior preserved when env vars
are unset.

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