Guard socket Redis reads before mutating room state

[mzl2233]

This adds explicit guards around Redis-backed room state reads before mutating participant or state data. Join now aborts with a socket error when Redis state cannot be read, leave and metadata updates stop instead of writing over uncertain state, and participant broadcasts are skipped when the participants read fails. Existing behavior is unchanged when Redis returns valid empty state.\n\nTested with:\n- node --check src/services/socket.service.js\n- node --check src/controllers/socket.controller.js\n\nCloses #5

[AnupamKumar-1]

Thanks for the PR — I tested this locally and found a semantic regression here.

getState() returning null does not always mean Redis failure. For fresh rooms it can also mean “uninitialized/missing key”.

Right now the new guard treats all null values as Redis failure, which causes healthy fresh-room joins to fail even when Redis is working.

Could you revisit the detection logic so it distinguishes:

• actual Redis failure
  vs
• valid empty/uninitialized state?