Markdown conversion doc + CLAUDE.md improve

CLAUDE.md

@@ -57,6 +57,13 @@ Fall back to Grep/Glob/Read **only** when the graph doesn't cover what you need.
 - A local MariaDB is expected to already be running on `127.0.0.1:3306` with the `file_converter` DB and `convert_user` credentials seeded.
 - Known pre-existing failures unrelated to any fix: `test/cleanup.test.js` ("deletes an expired pending job...") and `test/jobs/jobRepository.test.js` ("finds expired jobs and allows deleting them") — both fail on `main` independent of other changes (looks like a clock/timezone mismatch around `expiresAt` comparisons, not yet root-caused). Don't assume a change caused these; verify against `main` first if they show up again.
 
+### Manual end-to-end testing (starting server.js/worker.js yourself)
+
+- This dev machine typically already has its own long-running `node src/server.js` / `node src/worker.js` (and sometimes `npm run dev` for the frontend) processes started outside the session, from before any given conversation begins. Before manually verifying a change end-to-end, check for them first: `powershell -NoProfile -Command "Get-CimInstance Win32_Process -Filter \"Name='node.exe'\" | Select-Object ProcessId,CommandLine"`.
+- If a pre-existing worker is running, it loaded `src/converters/*.js` at its own start time and will keep running that in-memory code until restarted — it does not pick up edits made later in the session. If you start a *second*, freshly-spawned worker to test new converter code, both workers poll the same DB and race for pending jobs; if the stale one wins, the job fails with a misleading error (e.g. "No converter registered for X -> Y" for a pair that was, in fact, just added) even though the new code is correct. Don't conclude the new code is broken from a failure like this without first checking whether an older worker process grabbed the job.
+- Safe options once you notice this: only kill/clean up processes you started yourself in the session (identifiable by matching the exact command line you launched); never kill or restart the user's pre-existing `server.js`/`worker.js`/`npm run dev` instances without asking, since that's their running environment. If you want a real end-to-end confirmation, tell the user their existing server/worker needs restarting to pick up the change — don't restart it for them silently.
+- `curl -F "files=@/tmp/somefile"` fails with exit code 26 ("Failed to read local file") in this Git Bash environment when the path is under `/tmp`. Write the fixture under the project directory instead (e.g. `./scratch-test.md`) and reference it with a relative path in the `-F` flag; delete it afterward.
+
 ## Deployment (o2switch)
 
 - o2switch is shared hosting: no compiler toolchain, no root access. Any dependency with a native/binary component must ship as a precompiled binary — it cannot be built from source on the server.