feat: derive opencode instructions from Data Machine injectable memory files

[chubes4]

Summary

Extends the dm-agent-sync opencode plugin so the top-level instructions list is derived from Data Machine's registered injectable memory files instead of a static, hand-maintained array in opencode.json that silently drifts whenever a new memory file is registered in DM.

Closes #192. Depends on Extra-Chill/data-machine#2568 (the injectable-files command this consumes).

Problem

Two disconnected injection systems existed:

1. DM runtime AI calls — inject all registered memory files (incl. new ones like WAKE.md). ✓
2. opencode sessions — read a static instructions array in opencode.json that nothing keeps in sync with DM's registry.

dm-agent-sync previously only ran datamachine memory compose (refreshing composable files like AGENTS.md); it never touched the instructions list. So any memory file DM registers for injection was invisible to opencode sessions until someone hand-edited opencode.json — a latent drift bug for the whole class of "new memory file."

Fix

In the plugin's config hook, after the existing compose, call:

wp datamachine memory injectable-files --format=json

parse the resolved absolute paths, and write them into config.instructions. The opencode config(input) hook receives a mutable Config whose instructions?: string[] field we replace. Now any file DM registers for injection flows to opencode automatically — zero hand-edits, drift bug gone.

Graceful degradation

Leaves the existing instructions list untouched if:

• DM predates the command (call exits non-zero),
• output can't be parsed as JSON,
• or no paths come back.

DM already filters to on-disk files, so a registered-but-not-yet-written file (e.g. a briefing before its task first runs) can't break session load.

Layer boundary (correct split)

• data-machine (#2568) answers "which of MY files should inject?" — generic resolved paths, no opencode knowledge.
• this plugin owns "how opencode consumes that" — the injectable-files call + writing config.instructions. Runtime-specific code lives here, the only place it belongs.

Verification

• TypeScript transpiles clean (bun build bridges/kimaki/plugins/dm-agent-sync.ts).
• The consumed command was verified live in the DM PR (#2570 / data-machine#2568): for the primary agent it returns NETWORK/SITE/RULES/SOUL/USER/MEMORY — exactly the set currently hardcoded in opencode.json — so this swap is behavior-preserving today, and additive (WAKE.md etc.) once those land.

Note: homeboy lint on the local VPS dev box currently fails ESLint with a js-yaml parse error trying to load eslint.config.mjs via the legacy eslintrc loader — that's an environment/toolchain mismatch on this box (ESLint 8.57 + flat config), not a finding against this file (0 findings reported). CI uses its own pinned toolchain.

Constraints honored

• Conventional commit (feat:).
• No version bumps / changelog edits (homeboy-managed).