Rebuild the framework with smaller TLS buffers (ADR 0006)

custom_sdkconfig makes pioarduino regenerate the ESP-IDF libraries:
asymmetric TLS buffers (16 KB in, 4 KB out) and dynamic buffers that
free handshake-only data once connected. The rebuild also follows the
board: no PSRAM, 8 MB flash. The project now carries the partition
table the hybrid build needs (identical to the framework's: the app
slots must not move under updates over the air). Generated files are
ignored.

Debug Build, GNSS on, IRC on TLS: 78 KB free and a 59 KB low (M2 began
at 31 KB and 12.6 KB; the floor is 40 KB). The full stress set passes
on it: refused installs over Wi-Fi and from SD, put/get, screenshot,
core dump decode, Probation; under all of it at once, the low is 46 KB.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

.gitignore

@@ -4,3 +4,8 @@
 
 # Private signing keys never belong in the repository (ADR 0003)
 *key.pem
+
+# Generated by pioarduino's hybrid compile from custom_sdkconfig (platformio.ini)
+.dummy/
+managed_components/
+sdkconfig.*