chore: neutral wording for reviewer credits and contributor references

[jasperdew]

Comment, doc and diagnostic-message rewords so reviewer credits read as ordinary engineering. Issue numbers and reasons are unchanged everywhere.

What changed:

• Reviewer credits are now (review, #n); round labels read review P1/P2 (Dutch ronde kept where the surrounding text is Dutch).
• Temp paths use the project prefix (/tmp/pdfluent-*, pdfluent-google-creds.json); the credential file is a self-contained test fixture.
• Pointers to the contributor instructions and the territory map no longer name files outside the public tree.
• Generated-code notes say automatically generated; the cautions stay.
• The translation do-not-translate list loses one dead brand row nothing cites; the RFC changelog drops one emoji and one reviewer name (plus one v1.4 row the audit missed, same treatment).

Behaviour:

• Comments and docs except for three functional renames: the GitLab token keychain entry becomes pdfluent-api (see follow-up), the two benchmark target dirs move to fresh project-prefixed paths, and a few help/diagnostic strings are reworded (no test asserts the old wording — verified by search).

Owner follow-up (required): rename the GitLab token entry in the local keychain to pdfluent-api, or the two scripts and the runbook step that read it will fail to find it.

Deliberately untouched: the attribution guard and its test vectors (they must show the forbidden forms to refuse them), the seeding script and its test, the human co-author trailer docs and tests, the history note and its generator, the feature-claim denylist, the benchmark's configured model id (the value it must send), and the tests that mirror the real territory-map layout.

Overlap with #11: this PR edits files #11 proposes to delete (docs/SYSTEM_MAP.md, docs/release/FIRST_BETA_OPERATOR_RUNBOOK.md, docs/content-sync/, scripts/worker-prompt.md). Either order merges sanely; if #11 lands first, those hunks drop.

Checks run: py_compile over all touched scripts, bash -n over touched shell, TOML/YAML parse of touched configs, and the test suites for the touched guards (every_guard_has_a_job, mirror_has_not_drifted, a_deletion_declares_itself, feature_gated_tests_run) — all pass.