Skill/docs gaps: long builds, J-Link/Alif reset fallback, check the build result line, window tools

[MatthiasHertelArm]

Gaps in the agent-facing guidance; none needs code.

• Long builds. Neither cmsis-debug-live/SKILL.md nor the MCP docs mention that cmsis_action build may exceed the cap on pack resolution / first build, nor what the "still running" reply means. The skill never mentions timeoutMs or the 60 s cap at all (only references/cmsis-embedded-guide.md:80 and references/troubleshooting/embedded.md:44 do).
• Check the ✅ / ❌ line. The instruction to read the cmsis_action exit code instead of polling for files lives only in the tool description (debugMCPServer.ts:727-729); the skill only says "build first".
• J-Link reset on Alif E8. The reset tool verifies PC against the reset vector and reports "did NOT appear to have reset" honestly (debuggingExecutor.ts:1150-1252, J-Link dialect in resetAssist.ts:36-42), but the fallback the agent had to invent — stop the session and cmsis_action load_and_debug again — is undocumented. Add it to the skill and to the reset failure text; note that on secure-boot parts the nSRST line alone does not re-vector the core.
• Windows. Point agents at list_debug_windows / select_debug_window as the only way to discover and pick windows (see the control-token issue).
• Target running. Promote the "state = running → pause_execution first" table row to a rule, and list which tools are rejected while running.

Priority: P3, bundle with the P1 fixes.