refactor: collapse the two projects into one tree and move to npm

The repo held two near-duplicate projects. 2016/ and 2017/ each carried their
own React frontend, their own copy of the same Rust crate, and their own
package manager setup. 2016/tools/sync-from-thptqg2017.sh existed purely to
copy the parser source between them.

New layout:

  index.html + src/  the 2017 frontend, now the only one
  data/<id>/         2016, 2017, 2017-old, 2017-old2
  parser/            the single Rust crate, configs renamed to <id>.toml
  docs/              both projects' docs, 2016 copies suffixed -2016-legacy
                     pending the merge pass

<id> is now one identifier end to end: data/<id>/ feeds parser/configs/<id>.toml
and produces db/<id>.db.gz.

pnpm gives way to npm. pnpm-workspace.yaml existed only to whitelist
better-sqlite3's native build, which npm permits by default, so it has no
equivalent and is simply gone. Lockfiles cannot be converted; package-lock.json
is generated fresh. The migration direction is safe — pnpm's strict layout
forbids phantom dependencies, so anything that resolved under pnpm resolves
under npm's flat tree.

Adds parser/scripts/build-db.js and src/datasets.js: the four dataset IDs are
declared once and read by both the build tooling and (from the next phase) the
frontend.

Follow-on fixes the move made necessary:
  - eslint's Node-globals override pointed at scripts/, now parser/scripts/
  - crawl-baotintuc.js wrote to <root>/data, now data/2017
  - golden tests loaded configs by their old thptqg*-data.toml names

Drops the #[ignore]d Rust-vs-Node golden test. It shelled out to pnpm to run
scripts/build-database.js, a file removed when the parser was ported to Rust,
so it could never pass. check-duplicates.js and diff-datasets.js were already
broken before this change and are annotated as such rather than half-fixed.

63 Rust tests pass and clippy is clean from the new location.

parser/configs/2016.toml

@@ -0,0 +1,32 @@
+# thptqg2016 data/ — 4 .xls + 115 .xlsx mixed files.
+#
+# Three column layouts exist across the 119 files; the binary selects the
+# right one per-file at runtime via format_detection = "thptqg2016":
+#
+#   separate-scores  header SBD(0)/HOTEN(1)/TOAN(2)...  — dhhanghai files
+#   mapped           header SOBAODANH|SBD + DIEM_THI     — most provinces
+#   default          no header; positional 6-col layout  — remaining files
+#
+# This is the only dataset that populates ten_cum_thi and gioi_tinh, and the
+# only one whose files carry Tiếng Đức / Tiếng Nhật scores.
+#
+# sheet_mode = "all": several provinces overflow into Sheet2 (65k Excel row cap).
+# strip_blank_rows = false: no blank-row anomaly observed in this dataset.
+#
+# Table shape, INSERT and subject regexes are canonical — see src/schema.rs.
+
+format_detection = "thptqg2016"
+
+[reader]
+sheet_mode = "all"
+strip_blank_rows = false
+
+[validation]
+require_numeric_sbd   = false
+require_nonempty_name = true
+require_nonempty_sbd  = true
+
+[header]
+# Tokens that identify a header row by first-cell content (uppercased).
+# Covers both SOBAODANH-style and SBD-style headers.
+tokens = ["SOBAODANH", "SBD", "HO_TEN", "HOTEN", "HỌ TÊN", "STT"]

parser/configs/2017-old.toml

@@ -0,0 +1,25 @@
+# thptqg2017 data-old/ — 63 .xlsx files (pre-baotintuc refresh).
+#
+# sheet_mode = "first": single-sheet workbooks, never hit the 65k row cap.
+# SBD validation: require ^\d+$ (build-database-old.js:55 guard).
+# strip_blank_rows = false: no explicit blank-skip in build-database-old.js.
+#
+# Table shape, INSERT and subject regexes are canonical — see src/schema.rs.
+
+[reader]
+sheet_mode = "first"
+strip_blank_rows = false
+
+[columns]
+ho_ten      = 0
+ngay_sinh   = 1
+so_bao_danh = 2
+diem_thi    = 3
+
+[validation]
+require_numeric_sbd   = true
+require_nonempty_name = true
+require_nonempty_sbd  = true
+
+[header]
+tokens = ["HO_TEN", "HỌ TÊN", "STT"]

parser/configs/2017-old2.toml

@@ -0,0 +1,26 @@
+# thptqg2017 data-old2/ — 54 .xlsx files (corrected-export set).
+#
+# sheet_mode = "all": 24.HCM_UTLQ.xlsx overflows into Sheet2 (+6,446 rows).
+# SBD validation: require ^\d+$ (build-database-old2.js:57 guard).
+# strip_blank_rows = true: skip fully blank rows BEFORE counting sourceRows
+#   (build-database-old2.js:50-51 checks blank before sourceRows++).
+#
+# Table shape, INSERT and subject regexes are canonical — see src/schema.rs.
+
+[reader]
+sheet_mode = "all"
+strip_blank_rows = true
+
+[columns]
+ho_ten      = 0
+ngay_sinh   = 1
+so_bao_danh = 2
+diem_thi    = 3
+
+[validation]
+require_numeric_sbd   = true
+require_nonempty_name = true
+require_nonempty_sbd  = true
+
+[header]
+tokens = ["HO_TEN", "HỌ TÊN", "STT"]

parser/configs/2017.toml

@@ -0,0 +1,25 @@
+# thptqg2017 data/ — 63 .xls files from baotintuc.vn (current generation).
+#
+# sheet_mode = "all": Hà Nội and HCM overflow into Sheet2 (65k Excel row cap).
+# SBD validation: no numeric guard — build-database.js did not apply ^\d+$.
+# strip_blank_rows = false: no blank-row anomaly in this dataset.
+#
+# Table shape, INSERT and subject regexes are canonical — see src/schema.rs.
+
+[reader]
+sheet_mode = "all"
+strip_blank_rows = false
+
+[columns]
+ho_ten      = 0
+ngay_sinh   = 1
+so_bao_danh = 2
+diem_thi    = 3
+
+[validation]
+require_numeric_sbd   = false
+require_nonempty_name = true
+require_nonempty_sbd  = true
+
+[header]
+tokens = ["HO_TEN", "HỌ TÊN", "STT"]