SK-3061: make every bulk operation's README section iterate the response

[Devesh-Skyflow]

Summary

Bulk Insert's getTokens()-typed README snippet (added in #408) referenced record without ever introducing it:

for (Token token : record.getTokens().get("card_number")) {
    System.out.println(token.getTokenGroupName() + " -> " + token.getToken());
}

record doesn't exist on its own — it only comes from iterating insertResponse.getRecords(). Copy-pasting this snippet as-is wouldn't compile. Bulk Tokenize and Bulk Delete Tokens had the opposite gap: no response-reading snippet at all, just a JSON sample and prose.

Fix

Made all four bulk operations consistent — each section now has one code snippet that actually iterates getRecords():

• Bulk Insert: wrapped the existing Token snippet in the missing outer loop, plus a null check since getTokens() is null on a failed record.
• Bulk Tokenize: added a snippet with the outer loop over records and an inner loop over each record's tokens (it reports at two levels, per the paragraph above it).
• Bulk Delete Tokens: added a snippet with a single loop over records, branching on getError().
• Bulk Detokenize: already had one (added in SK-3061: make DetokenizeResponseRecord.getMetadata() typed #410) — used as the reference pattern for the other three.

Docs-only change — no source/test/baseline changes.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (flowvault-release/26.8.13@454f3ec). Learn more about missing BASE report.

Additional details and impacted files

@@                     Coverage Diff                      @@
##             flowvault-release/26.8.13     #411   +/-   ##
============================================================
  Coverage                             ?   91.37%           
  Complexity                           ?       28           
============================================================
  Files                                ?      158           
  Lines                                ?     6448           
  Branches                             ?      861           
============================================================
  Hits                                 ?     5892           
  Misses                               ?      362           
  Partials                             ?      194           

Flag	Coverage Δ
unittests-flowvault	89.93% <ø> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
Module: common	88.39% <0.00%> (?)
Module: skyvault	94.72% <0.00%> (?)
Module: flowvault	88.92% <0.00%> (?)
Service Account	86.69% <0.00%> (?)
Vault Data	91.81% <0.00%> (?)
Vault Tokens	99.03% <0.00%> (?)
Vault Connection	100.00% <0.00%> (?)
Vault Controller	85.31% <0.00%> (?)
Detect	100.00% <0.00%> (?)
Audit	100.00% <0.00%> (?)
BIN Lookup	100.00% <0.00%> (?)
Config	96.26% <0.00%> (?)
Utils	89.18% <0.00%> (?)
Errors	100.00% <0.00%> (?)
Enums	100.00% <0.00%> (?)
Logs	95.34% <0.00%> (?)

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