feat(config): lens sections - a repository's own text appended to a shipped charter

A lens has one charter, the one this pipeline ships; what a repository
knows that is not general to the lens - its platform and layers, the
record it keeps its decisions in, what its users already have, the
calibration entries that are its own - goes in a file the config names
for the lens (lenses.<name>.section), and Charter appends it after one
blank line. The charter sha in every reuse key covers the combined text.

The config refuses a path outside the repository - absolute, or
climbing out with `..` - by the check slots.dir had, now one both
settings share; a file missing or one the run could not use (a dangling
link, unreadable, not UTF-8) is a problem too, checked through the
reader Charter uses (Prompt::ReadSection), so a section is never
dropped in silence, and a name that is no lens is the unknown key it
always was. Nothing lists a directory, so what lies beside the files is
no concern of the config's: a directory listed would have to tolerate or
refuse every foreign entry. The run logs which charters got one.

The better-solution charter gains a consumer's general entry
(2026-10-31: a mechanism reworked a second time in one submission is the
signal to derive the fix at every layer the data crosses). The procedure
names the section wherever it names the charter: among the config's keys,
in the lens inputs, in the reuse rule (an edit to either re-runs the lens)
and in the feedback loop, which routes a repository's own lesson to its
section and a general one to the shipped charter.

process/prepush.md

@@ -32,7 +32,8 @@ hash at Gate 5.
   — content, history and blame; the state before the range via
   `git show <base>:<path>`.
 - `--context-paths` for the evidence dirs the commit messages' claims rest on.
-- The lens charter (`process/lenses/repo-*.md`, system text
+- The lens charter (`process/lenses/repo-*.md`, with the repository's own
+  section, `lenses.<name>.section`, appended; system text
   `_common-repo.md`) and the dispositions in force.
 - A lens with the `browser` or `browser+supabase` environment (the
   functional lens by default; `lenses.<name>.environment` in the config):
@@ -159,7 +160,14 @@ is empirical and needs one with the browser while it runs; the static
 lenses default to `none` and may take any. A verdict bought in one
 environment is never reused, resumed or salvaged in another, and a defect
 found in one drops the clean verdicts the lens holds for the same code in
-the others), `supabase`, the database under test for every lens with
+the others; `section`, a file of the repository's own — a relative path
+inside it — appended to that lens's shipped charter after one blank line:
+the calibration entries and conventions that are this repository's rather
+than the lens's, which has the shipped charter for what is general to it;
+the reuse keys carry the combined text's hash; a path outside the
+repository and a file missing, unreadable or not UTF-8 (a dangling link
+included) are config problems, a name that is no lens an unknown key),
+`supabase`, the database under test for every lens with
 `supabase` or `browser+supabase`: `dbUrl` (the local stack's Postgres —
 this machine only; masked in the dump and the log), `start` / `stop` (how
 the operator brings the stack up when no lens drives the application;
@@ -360,9 +368,10 @@ the functional lens):
   never stored, so it runs on the next hash whatever changed;
 - every code unit and both whole passes: the range base (a rebase re-runs
   all of them);
-- as always: the lens charter, the prompt version, the model, the
-  dispositions in force. An edit to a `repo-*.md` charter re-runs that lens
-  on the next hash; a re-run on the SAME hash resumes and salvages by hash and
+- as always: the lens charter (the shipped text with the repository's
+  section), the prompt version, the model, the dispositions in force. An
+  edit to a `repo-*.md` charter, or to the repository's section of it,
+  re-runs that lens on the next hash; a re-run on the SAME hash resumes and salvages by hash and
   model alone (use `--no-reuse --no-salvage` there).
 
 What is stored as reusable: a pass that itself returned no undischarged
@@ -470,8 +479,10 @@ can still reject (a fixture repository with one planted defect per gate;
 
 A defect that reaches a pushed release, or a review comment on the
 repository nobody's lens predicted, is a process bug: post-mortem it and
-append a dated calibration entry to the `repo-*.md` lens that should have
-caught it, or here. The entries dated before 2026-10-15 were carried from the
+append a dated calibration entry where the lesson belongs: a lesson of
+this repository's in its own section of the lens that should have caught
+it (`lenses.<name>.section`), one general to the lens in the shipped `repo-*.md`
+charter, one of the mechanics here. The entries dated before 2026-10-15 were carried from the
 pipeline's earlier home because they are rules of the mechanics, not of one
 repository.