fix(telegram): clear send_path_degraded immediately on successful reconnect

[liuhao1024]

What does this PR do?

Clears _send_path_degraded immediately after a successful start_polling() reconnect, instead of deferring it to the 60-second heartbeat probe. This prevents all outbound send() calls from being blocked for 60 seconds after the Telegram gateway recovers from a network interruption.

Related Issue

Fixes #35205

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)

Changes Made

• gateway/platforms/telegram.py: Clear _send_path_degraded = False immediately after successful start_polling() in _handle_polling_network_error(), alongside the existing _polling_network_error_count = 0 reset. Added comment explaining the rationale.
• tests/gateway/test_telegram_send_path_health.py: Updated test_reconnect_storm_sets_and_heartbeat_clears_flag → test_reconnect_clears_degraded_flag_on_successful_start_polling to verify the flag is cleared immediately. Added test_degraded_flag_stays_true_when_start_polling_fails to verify the flag remains True when reconnect fails (negative case).

How to Test

1. Run pytest tests/gateway/test_telegram_send_path_health.py -v — all 4 tests should pass
2. Run pytest tests/gateway/test_telegram_network_reconnect.py -v — all 15 tests should pass (no regressions)
3. Manual: trigger a Telegram network error (e.g., disconnect WiFi), reconnect, and verify outbound messages are delivered immediately without the 60-second delay

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/ -q and all tests pass
• I've added tests for my changes (required for bug fixes, strongly encouraged for features)
• I've tested on my platform: macOS

Documentation & Housekeeping

• I've updated relevant documentation (README, docs/, docstrings) — or N/A
• I've updated cli-config.yaml.example if I added/changed config keys — or N/A
• I've updated CONTRIBUTING.md or AGENTS.md if I changed architecture or workflows — or N/A
• I've considered cross-platform impact (Windows, macOS) per the compatibility guide — or N/A
• I've updated tool descriptions/schemas if I changed tool behavior — or N/A

Code Intelligence

• Analyzed: gateway/platforms/telegram.py TelegramAdapter._handle_polling_network_error (called by polling error callback, triggers reconnect ladder)
• Blast radius: LOW — single flag reset in a well-isolated error recovery path; send() retry logic handles stale pool case
• Related patterns: _verify_polling_after_reconnect() heartbeat probe still runs as secondary safety net; _drain_polling_connections() resets polling pool but not general request pool (documented limitation)

[teknium1]

Automated hermes-sweeper review: this fix is already implemented on current main.

Evidence:

• plugins/platforms/telegram/adapter.py:1765 resets _polling_network_error_count, then clears _send_path_degraded = False immediately after start_polling() succeeds, before the deferred heartbeat probe is scheduled.
• tests/gateway/test_telegram_send_path_health.py:106 includes the Telegram gateway: send_path_degraded stays true after successful reconnect, blocking all outbound messages #35205 regression test proving a successful reconnect clears the flag without relying on _verify_polling_after_reconnect() and allows send() to work immediately.
• The implementation landed in commit 2ecb6f7fe60f6a240d632bbd51bcbb25ad22c161 / PR fix(telegram): clear send_path_degraded on successful reconnect (#35205) #54076, which also closed the linked issue Telegram gateway: send_path_degraded stays true after successful reconnect, blocking all outbound messages #35205.

Thanks for the original fix and tests here — the same behavior has since landed on main, so this PR is redundant now.