feat(plugin): pass sessionID and callID to shell.env hook input

[tesdal]

Fixes #13661

What does this PR do?

Adds optional sessionID and callID fields to the shell.env hook input, for symmetry with other events + state correlation when using concurrent subagents.

The fields are optional because pty/index.ts has no session context. bash.ts and prompt.ts already have both values in scope -- just passing them through.

How did you verify your code works?

• Confirmed ctx.sessionID and ctx.callID are in scope at bash.ts:166
• Confirmed input.sessionID and part.callID are in scope at prompt.ts:1625
• pty/index.ts unchanged -- fields are optional, undefined is correct there
• Existing plugins unaffected -- new fields are additive on the input object
• Logged from plugin
  {"type":"debug","timestamp":"2026-02-15T00:03:14.492Z","level":"debug","message":"[shell.env] cwd=opencode sessionID=ses_3a1643f0dffeF2LkERFvZ6xOMw callID=toolu_vrtx_012mf7oncgJQaP6qf13pEGGg"}