feat(reliability): add coding-safe compression profile

[alteixeira20]

Problem

For coding agents, reducing every eligible block is not the same as preserving exact working state. Authority text, tool schemas, live source/tool output, diffs, diagnostics, paths, and identifiers are materially riskier to change modality than old closed conversation history.

Changes

• add explicit coding-safe, balanced, aggressive, and passthrough profiles;
• preserve the existing upstream behavior when PXPIPE_PROFILE is unset;
• keep tools and live tool results native in safe profiles;
• limit safe compression to sufficiently old, closed history;
• add a conservative keep-sharp classifier for code, diffs, diagnostics, stack traces, structured state, paths, and machine identifiers;
• prevent caller overrides from weakening that guard;
• keep safe-profile model admission limited to upstream's existing evidence-backed default models;
• expose profile-local library/applicability APIs;
• wire profile selection into the Node host;
• add provider-neutral regression contracts for schemas, Responses call/output ordering, native images, response bytes, and provider headers.

Scope

No AGY aliases, Codex routing, provider router, dashboard redesign, model promotion, or cache optimizer.

The unset-profile behavior is intentionally unchanged.

Validation

Validated from a branch based directly on current upstream 0.13.1:

• production dependency audit;
• TypeScript typecheck;
• focused safety/contracts tests;
• full test suite;
• build;
• Worker dry-run;
• git diff --check.

No raw prompts, credentials, session files, machine identifiers, or temporary validation machinery are included.