feat(compressor): smart collapse, dedup, anti-thrashing, template upgrade, hardening

Combined salvage of PRs #9661, #9663, #9674, #9677, #9678 by kshitijk4poor.

- Smart tool output collapse: informative 1-line summaries replace generic placeholder
- Dedup identical tool results via MD5 hash, truncate large tool_call arguments
- Anti-thrashing: skip compression after 2 consecutive <10% savings passes
- Structured action-log summary template with numbered actions and Active State
- Hardening: max_tokens 1.3x cap, multimodal safety, note idempotency, adaptive cooldown

Follow-up fixes applied during salvage:
- web_extract: reads 'urls' (list) not 'url' (original PR bug)
- Multimodal list content guards in dedup and prune passes
- Kept 'Relevant Files' section in template (original PR removed it)

Skipped PRs #9665 (user msg preservation — duplication risk) and #9675 (dead code).

Author: kshitijk4poor