fix(gateway): close /proc cmdline file handle in PID scan loop

[annguyenNous]

Problem

_find_gateway_pids_by_profile() in hermes_cli/gateway.py opens /proc/{pid}/cmdline for every numeric PID entry without closing the file handle. On busy systems with hundreds of PIDs, this leaks file descriptors.

Fix

Use a with statement for deterministic cleanup:

with open(f"/proc/{pid}/cmdline", "rb") as fh:
    cmdline = fh.read().decode("utf-8", errors="replace")

[alt-glitch]

Duplicate of #27910 — both fix /proc/{pid}/cmdline file descriptor leak in the PID scan loop (bare open() without context manager). #27910 targets _find_hermes_pids(), this PR targets _find_gateway_pids_by_profile() in the same file. Same fix pattern (add with statement), introduced by #22860.

[teknium1]

Thanks for the focused resource-leak cleanup. An automated hermes-sweeper review found that this exact fix is already present on current main, so I’m closing this as implemented_on_main.

Evidence:

• hermes_cli/gateway.py:455 now uses with open(f"/proc/{pid}/cmdline", "rb") as _f: and reads from that handle at hermes_cli/gateway.py:456, so the descriptor is closed immediately.
• The implementing commit is d4b533de4edd2211125dfe3904959d1cd41c5642 (fix: batch of small robustness/correctness fixes from @kyssta-exe), whose commit message explicitly lists the gateway /proc/<pid>/cmdline fd-release fix.
• git tag --contains d4b533de4 shows the fix is contained in v2026.6.5.

The prior duplicate note linking this to the same leak pattern as #27910 was useful context; the current main code now covers this PR’s requested behavior.