feat: include retry history in JSON output for send commands

[dapi]

Problem

When using --json mode, logSendRetry is completely suppressed — retry attempts produce zero output. If a command retries multiple times and eventually succeeds or fails, the user in JSON mode only sees the final result with attempts: N but has no visibility into what happened during retries.

Current Behavior

tgcli send photo --to @chan --photo ./img.png --retries 3 --json
# Output (success after 2 retries):
{"ok":true,"method":"sendPhoto","message_id":123,"attempts":3}
# No information about WHY it retried or what errors occurred

Proposed Solutions

Two complementary approaches:

Option A: Add retry log to final JSON payload

{
  "ok": true,
  "method": "sendPhoto",
  "message_id": 123,
  "attempts": 3,
  "retry_log": [
    {"attempt": 1, "error": {"type": "network", "message": "ECONNRESET", "code": "ECONNRESET"}},
    {"attempt": 2, "error": {"type": "network", "message": "ECONNRESET", "code": "ECONNRESET"}}
  ]
}

Option B: Write retry progress to stderr in JSON mode

Retry logs go to stderr (not stdout) so JSON parsers aren't affected.

Recommendation

Option A is more useful for programmatic consumers. Option B is simpler to implement. Both can coexist.

Context

Found during PR #18 review by silent-failure-hunter agent.

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