docs(L1): add goquarkchain bugfix retro + lock call-chain docs

[ping-ke]

Summary

Adds four documents to pm/L1, distilling three weeks (2026-06-14 ~ 07-05) of goquarkchain bug-fix work into reusable guidance for goshard's design and development. goquarkchain is being deprecated, so the goal is to capture root causes and process lessons rather than let the effort stop at "it's fixed."

Two of these (retro + locking) are provided in both Chinese and English.

Files

• L1/goquarkchain-bugfix-retro.md — three-week bug-fix retrospective (Chinese)
• L1/goquarkchain-bugfix-retro.en.md — same, English
• L1/locking.md — MinorBlockChain lock call-chain reference (Chinese)
• L1/locking.en.md — same, English

What the retrospective covers

• The incident storyline: how 6~7 individually non-fatal bugs stacked into a self-perpetuating deadlock loop that survived crash-restart (root race between AddBlock and AddRootBlock, typed-nil panic, marker/body inconsistency, sync batch abandonment, etc.).
• Bug branch inventory: each fix branch / PR, its type, and status.
• Pitfalls working with AI: the recurring failure modes (keeps getting more complex, reverts on test failure instead of understanding it, doesn't recognize existing changes, carries a flawed premise all the way through) and the countermeasures.
• Why it took so long: repeated modification, AI-interaction cost, and the slow "run node + watch logs" verification loop.
• Ten takeaways for goshard: seven technical design principles (reuse Geth, no out-of-lock patch-up writes, lock-vs-performance balance, deterministic race tests, define locks before use, separate local vs global semantics, validate length prefixes before allocating) plus three process/collaboration ones (frame scope/premises/structure up front, commit in small steps, engineering constraints for AI-assisted work).
• Direct value to goshard: much of goshard is copied from goquarkchain — especially the QuarkChain-specific, Geth-referenceless logic that was this bug chain's disaster area — so these fixes harden the very code goshard reuses.