refactor(mode): modes are collaboration states — drop the access cap; enforcement axes stay independent

Review follow-up (tianyicui): plan mode and the sandbox are orthogonal
AXES, not just orthogonal state — entering plan must not change what the
sandbox enforces, matching Codex's separation of Plan/Default
collaboration presets from sandbox and approval settings.

ModeDefinition.access, the bash/resolve-mode clamp, and both cap-derived
guards are removed; a ModeDefinition is exactly { section }, and a mode
now carries only its guidance section plus the exit_plan_mode review.
The bash seam's resolveMode + waterfall go with their only listener:
dsh-bash and dsh-tool-bash revert to master byte-for-byte, and the
dsh-mode → dsh-bash dependency edge is gone. A deployment that wants
kernel-enforced read-only planning pairs the mode picker with the
independent sandbox-mode option, in either order.

The RFC archives this as the second removed enforcement shape (after
the interim allowlist) with the same restart trigger — effects
self-declaration; the orthogonality FAQ now answers with the two-axis
rule. The plan example demonstrates the axes side by side, and the
re-recorded fixtures pin the guidance-only section.

pnpm-lock.yaml

@@ -1001,9 +1001,6 @@ importers:
       '@deepseek-ai/dsh-agent-loop':
         specifier: workspace:^
         version: link:../../core/agent-loop
-      '@deepseek-ai/dsh-bash':
-        specifier: workspace:^
-        version: link:../../bash/bash
       '@deepseek-ai/dsh-code-runtime':
         specifier: workspace:^
         version: link:../../code-runtime/code-runtime